Prebiotic Petroleum

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Initialization of metabolism in prebiotic petroleum

abstract

   The theoretical and bibliographical work on the geochemical origin of life, which I present here, it works on the assumption that:
"The class of most complex molecules of life that can have a geochemical and abiotic origin is the class of fatty acid with long aliphatic chain".

   This idea comes from the controversy over the abiotic oil industry, and the first measurements of abiotic oil at mid-ocean ridges ( Charlou J.L. et al. 2002, Proskurowski G. et al. 2008 )*. To go further and propose a comprehensive experimentation on the origin of life, I propose in this article the idea that the prebiotic soup or prebiotic petroleum would stem from the diagenesis of the gas clathrates/ sediments mixture. Gas, H2S H2 N2 CH4 CO2, are produced at mid-ocean ridges, and at large-scale at the seafloor, by serpentinization. Sediments contain hydrogenphosphates as a source of phosphate and minerals to the surface catalysis.

   Extreme conditions experienced by some prokaryotes and pressures and temperatures of submarine oilfields of fossil petroleum are close. The hydrostatic pressure is around 1.5 kbar and the temperature is below 150 ° C.

   This experiment I propose is quite feasible today since these conditions are used

  • in research and exploration of fossil petroleum;
  • in the field of organic chemistry called "green chemistry" and where temperatures remain low and the pressure can reach 10 kbar (RV Eldik et al. 2008) *;
  • to study the biology of prokaryotes living in the fossil petroleum of industrial interest. These studies are quite comparable to experiment with prebiotic oil;
  • Finally, this experiment can be based on research on abiotic CH4 on Mars and abiotic hydrocarbons on Titan.

   The next step in the theoretical research of the origin of life is the abiotic synthesis of liposomes. Abiotic synthesis liposomes just requires synthesis of glycerol and ethanol-amine (or serine) esterifying the phosphate and fatty acid. The state of research on the abiotic synthesis of these molecules shows that those of the serine, ethanol-amine as well as the 1st stage of the formose reaction (Glyceraldehyde, dihydroxyacetone and glycolaldehyde) are quite possible in prebiotic soup after diagenesis of gas clathrates, mainly due to the presence of H2. For cons, the synthesis of glycerol in the laboratory and in industry are so drastic and complex that I proposed to initialize the metabolism in fatty acid vesicles, hydrogenation by H2 of glyceraldehyde-P or DHA-P (dihydroxyacetone phosphate) glycerol-3P after esterification to the fatty acid, the hydrogenation is facilitated by the catalyst power of the multi-anionic surface of these vesicles.

   This idea, I detail it in the article "prebiotic chirality" where I show that the mechanical cohesion of the liposome is at the origin of homochirality of sugars and amino acids, and it accelerates metabolism initialization . In this article I have made a draft dozens of steps in the evolution of prebiotic metabolism.

   I also wrote a third article, "chemo-osmosis prebiotic" to outline the implementation of ion channels, essential to liposome communication with its environment. Initialization of ion channels is based on the zwitterionic nature of the phospholipids, the mechanical cohesion of the liposome and the electrical potential across the bilayer. This electric potential is at the origin of prebiotic chemo-osmosis, motor continuity of molecular evolution.

   This article will on the prebiotic oil is the basis of all these works.


   * See article for detailed references.
   Publication of articles in Wikiversity:
   https://en.wikiversity.org/wiki/Prebiotic_Petroleum
   https://en.wikiversity.org/wiki/Prebiotic_chemo-osmosis
   https://en.wikiversity.org/wiki/Prebiotic_chirality.

français

Note on 14.03.2015: This article is part of the summary of my work until 2014, published in Origins of Life and Evolution of Biospheres, March 2015.
Reference: Prebiotic Petroleum; Mekki-Berrada Ali, Origins of Life and Evolution of Biospheres, 2015, DOI 10.1007/s11084-015-9416-7.[1]

Introduction[edit]

    This work is a theoretical research on molecular evolution that occurs in the abiotic oil, which could lead to the emergence of life. A pocket of abiotic oil similar to that of fossil petroleum is an ideal environment for studying the origin of life. This is a closed medium, stable, rich in organic molecules and inorganic catalysts, evolving and going back up from geological depths of the earth's crust to the surface. Gradually moving the physicochemical conditions of extreme depths to those of the surface, compatible with life, any imaginable molecular evolution is possible.
    Synthetic oil, could be used in an abiotic experiment. But it is synthesized by the industrial process of Fischer-Tropsch from synthesis gas (CO+H2), itself synthesized either from coke (C+H2O) or natural gas (CH4+H2O), both are from fossil origin. To achieve an abiotic oil, similar to fossil petroleum, its synthesis must be done in the presence of elements NPS, with molecules of abiotic origin, in depth, in the crust and go back up soaked in a porous rock, without any molecule of origin biogenic.
    Before studying the initialization of metabolism in this context, we will establish the state of knowledge on the geochemical processes producing a abiotic oil, with abiotic NPS elements.

State of research on the pocket of abiotic oil.[edit]

    It will be rather the state of research on the elements which compose the pocket. Because no work has been done so far about it. These elements are hydrocarbons and water (H C O), the free phosphate (P) and ammonium (N). We will not study sulfur (S) especially because its molecular species involved in the living, sulfides, sulfates and S element itself are ubiquitous in the lithosphere and hydrosphere.

    For nitrogen, NH4+ is the more abundant species in depth at high pressures and high temperatures, because in the mineral it replaces the potassium ion K+. Nitrogen is represented by nitrate because ammonium is used directly by the bacteria. Dinitrogen N2 dissolved in pore water at 11 ppm, can be reduced to NH4+ in the presence of H2 in hydrothermal fluids which is not the case on the surface and in the pocket of fossil petroleum.

In the field[edit]

Phosphate[edit]

  • Phosphorus is found at 700 molar ppm ( 1050 ppm by weight ) in the crust in the form mostly of phosphate ions incorporated into insoluble apatite and 0.04 ppm molar (2µmol/kg, Broecker & Peng [2] 1982) in ocean water as free phosphate.
  • At temperatures generally reached in magmas, 1000-1400°C, a fraction of phosphate ions in the liquid magma polymerizes to form polyphosphates. Yamagata [3] & al. (1991) has shown that polyphosphates are present in the hydrothermal solutions at a concentration of the micromolar range.
  • According to Arrhenius [4] & al. (1997), in seawater (Mg/Ca ~ 5 and pH < 8.5 ) the phosphate from leaching of the land surface, precipitate as an amorphous solid of hydrogen phosphates of Ca and Mg (brushite, CaHPO4.2H2O and newberyite, MgHPO4.3H2O).
This solid crystallizes in whitlockite, HMgCa9(PO4)7, able to give oligo-phosphates under the conditions of temperature and pressure of contact metamorphism or those of hydrothermal surface. According to Arrhenius [4]today living things use the hydrogenphosphates and turn them into apatites. And, at origins of life, the oligophosphates should be very available.
  • We find the whitlockite as secondary mineral in granitic pegmatites and in abundance in extraterrestrial environments: meteorites, the Moon and Mars.

Ammonium.[edit]

  • Nitrogen is present at 35 ppm by weight (50 ppm molar) in the earth's crust in the form of ammonium ions that replace potassium ions in igneous rocks. (Hall [5] 1999, Stevenson [6] & al. 1962) .
According to Hall the majority of the ammonium is of sedimentary origin, but some is of magmatic origin. The sedimentary origin is incorporated predominantly by hydrothermal alteration, the rest by contact metamorphism. Ammonium igneous rocks can be extracted by vacuum pyrolysis at 1000°C under standard pressure (Hall [7] & al. 1993). Which is perhaps the conditions of the upper mantle.
  • Nitrates, very rare, are represented by the evaporites on the surface. Nitrate dissolved in the oceans represente only 0.6 ppm molar (30 µmol/L, Broecker & Peng [2] 1982).
  • In seawater and interstitial waters dinitrogen is the predominant form with 11 ppm molar (590 µmol/L, Broecker & Peng [2] 1982 ); dinitrogen can be reduced to NH3 by H2 hydrothermal fluids.

Abiotic oil.[edit]

   This is essentially the process that has been studied serpentisation field for research abiotic oil. And particularly at mid-ocean ridges and first kilometers deep subduction zones.

  • Mid-ocean ridges
Mid-Ocean ridges are spread over 60,000 km and are dotted regularly with hydrothermal vents that produce on long periods H2S, CH4, H2, N2 and CO2. These five gases are quenched to 2°C, the temperature of the seabed at the output of sources and are found on the ocean floor, at pressures of 100 to 400 bar and where they can form clathrates gas. Away from the axis of the ridges, they will be gradually covered by sediment containing phosphate hydrogénates we saw above.
Here is a condensed, campaign results of measurements made in seven hydrothermal vents of the Atlantic, according Charlou [8] & al. (2002), table 1.

Tableau 1. The gases produced in the atlantic ridges.
Gaz
mmol/kg
number
of sites
intervalle    Sea water
CO2 6 5.2 - 28 2.30
N2 6 .9 - 3 .59
H2S 7 .5 - 11 0
CH4 7 .023 - 2.63 .0003
H2 7 .020 - 16 .0004
δ13C CH4
en ‰
6 -8 . -19,6 -
Rainbow site (Charlou [8] et al. 2002, table 3), measurements were made in 1997, 1998, 1999 and 2001. They do not vary much.
Moreover, the extent of isotopic fractionation of 13C in CH4 (d13C) suggests an abiotic origin. Methane would be synthesized by the Fischer-Tropsch process.
The abiotic methane was studied in more detail by Proskurowski [9] & al. (2008), showing an increase of C2H6 and C3H8 for d13C with carbon numbers, consistent with the theory of abiotic fractionation.
  • Subduction zones
In the contact between two plates in subduction, geochemical processes are multiple and complex, due to enormous forces brought into play, without relation to what is going on oceanic ridges. At the level of oceanic trenches, pressures can reach the kbar and temperature of only 2°C.
At firsts kms depth so these are processes at low temperature and high pressure that are in action. The blue-facies and is at 15-18 km depth with pressures above 6 kbar and temperatures between 200 and 500°C. Ultramafic rocks will change into lizardite, which are serpentinites. According to the synthesis of serpentinites made ​​by BW Evans [10] (2004), serpentinization may occur between 50 and 300°C temperature and in a wide range of pressure, 0.1 kbar to 10 kbar (figure 5 [10]), to give the chrysotile ( Mg3Si2O5(OH)4 ) and lizardite ( Mg3Si2O5(OH)4 ), with production of H2 and magnetite.
Beyond 18 km depth, serpentinization of ultramafic rocks give antigorite ( (Mg,Fe++)3Si2O5(OH)4 ), without production of H2 or magnetite at a temperature between 400 and 600°C (Evans [11] 2010).
In subduction zones, these are the only results we can deduce indirectly from the study of rocks and magnetic anomalies and seismic zone at the front of the volcanic arc.
Otherwise many surface phenomena suggest that there is production of hydrocarbons, but we do not know, until now, they are likely fossil or abiotic. These are:
  1. Mud volcanoes at the front of the arc, which emit lots of methane.
  2. Gas hydrates identified by new techniques along subduction zones, with a length equivalent to the oceanic ridges. These deposits are not yet exploited.
  3. Gas shales and oil shales, rocks from the metamorphic zones.
  4. Volcanic gases including CH4, H2 and NH3.
It should be remembered also the strong hydrothermal ascending circulation, produced by the vaporization of water and gases which saturate the subducting oceanic crust. These hydrothermal fluids transporte NH4+ that replace the K+ ions in the metamorphic rocks, and the free phosphate as we have seen (Yamagata Y. et al. 1991) [3].

In laboratory[edit]

   Abiotic laboratory experiments are much more numerous and varied as the field measurements, and they relate to three key molecules that are methane, ammonia and phosphate. Comparing the synthesis of these three molecules in Table 2, is justified because they and the molecules that give them birth, that is, H2, CO2 and N2 are always found together in the hydrothermal fluids. And this is quite adequate for the formation of pockets of abiotic oil containing the NPS.
   The experiments reported in Table 2, were not all made ​​in the same spirit, nor the aim of abiotic pocket. However the results are consistent with the formation of a pocket of abiotic oil. The main lessons we can draw are:

  1. These processes occur in a narrow temperature range of around 300°C;
  2. The pressure can vary widely for the same process, up to 2 orders of magnitude, but remains below 10 kbar for all processes.
  3. The supercritical hydrothermal experiments can be compared with the industrial processes in the gas phase at low pressure. Steam reforming was added because it can occur in subduction, as evidenced by the volcanic gases from subduction arcs.
  4. The catalysts used, including iron, its oxide and nickel are abundant in the lithosphere.
  5. Note the importance of mineral surfaces in industrial processes. It is essential that the experiences under the "pocket abiotic" are made in suitable porous rocks.
  6. The hydrothermal experiments were motivated by the assumption that the origin of life occurred (or occurs) at mid-ocean ridges. Now it is evident that the immediate quenching of H2, CO2 and N2, in cold water from the floor should not favor any of the processes of Fischer-Tropsch and reduction of N2 by process type Haber-Bosch. But the results are interesting because the experiments are performed at high pressure and high temperature conditions which are those of subduction zones. Well this is interesting for processes in gas hydrates, we saw earlier, when They are covered with few km of sediments while undergoing heat of the floor which is cooling.
  7. McCollom [12] has been shown, line e.j on the table, that discrimination between biotic and abiotic based on the fractionation of carbon 12 and 13 was not valid for methane. That's why to demonstrate the nature of abiotic hydrocarbons at the oceanic ridges, Proskurowski [9] had to do for higher hydrocarbon chains. This observation is of great importance for the future, because if the origin of life was made ​​in the abiotic oil, then beings from this oil could transform, or only enrich, with their membranes, abiotic hydrocarbons witj biotic hydrocarbons. Hence the origin of crude biotic called fossils.
  8. These experiments should be redone in the hypothesis of the pocket of abiotic oil, particularly for phosphates to the same pressures as other experiments.
Table 2. Abiotic processes
Process reactions Products Temperature °C Pressure bar
a Steam reforming CH4+H2O CO H2 800-900 25
b Serpentinisation ridges, seabed FeO+H2O H2 N2 CH4 CO2 50-300 100-10000
c Serpentinisation subduction 15km FeO+H2O H2 (N2 CH4 CO2 ?) 200-500 6000
d Fischer-Tropsch gas CO+H2 Pétrole dont acides gras 220-350 25-45
e,j Fischer-Tropsch hydrothermal CO2+H2 Pétrole dont acides gras 250 325
f Haber-Bosch gas N2+H2 NH3 500-600 200-300
g Haber-Bosch hydrothermal N2+H2 NH3 700 1000
h Haber-Bosch hydrothermal N2+H2 NH3 200 55
i Arrhenius heating MgHOPO3+H2O OH(H2PO3)nH 100-500 1
a. Steam reforming :
CH4 + H2O = CO + H2;
T= 800-900°C, P= 25 bars, catalysts: Ni, CuO, Zn, mineral surfaces.
  • Serpentinisation
(Mg,Fe)SiO4 + H2O = Mg3Si2O5(OH)4 + Mg(OH)2 + Fe3O4 + H2 , or
olivine + water = serpentine + brucite + magnetite + hydrogen and come down to
2(FeO)rock + H2O = (Fe2O3)rock + H2
b. Serpentinisation ridges, seabed
Reproduction of serpentinisation in laboratory and modelisation :
McCollom [13] 2009, modelisation ;
B.W. Evans [11] 2010, experimentation.
Temperature of 50 to 300°C, Pressure of 100 bars to some kbars.
Holm [14] 2006 : considers that on the floor serpentinization is continuously at temperatures around 150°C.
c. Serpentinisation subduction at 15km
Evans [10] (2004).
Temperature of 50 to 300°C, Pressure of 6 kbar.
(2n+1)H2 + nCO = CnH(2n+1)-X + nH2O
   X = H, aliphatic chains whose methane, ethane...
   X = OH, alcohols whose methanol, ethanol and alcohols in alpha and with long aliphatic chain ....
   X = CO2H, carboxylic acids whose formic, acetic and fatty acids with long aliphatic chain ....
   X = CHO, aldehydes whose formaldehyde, acetaldehyde and aldehydes with long aliphatic chain ...
   X = CH=CH2, olefins whose acetylene and propylene and olefins in alpha with long aliphatic chain ...
d. Industrial process, phase gas: Kreutz [15] et al. 2008
T= 220-350°C, P= 25-45 bars; catalysts: Fe, mineral surfaces.
e. Hydrothermal conditions, McCollom [16] 1999:
T= 175°C, P= 325 bars; catalysts: montmorillonite + alumine.
j. Isotopique fractioning, McCollom [12] 2006:
Demonstration of non-discriminating isotope fractionation of carbon 12 and 13,
Fischer-Tropsch process and hydrothermal conditions, T= 250°C, P= 325 bars; catalyst: Fe.
N2 + 3 H2 = 2 NH3
f. Industrial process, phase gas (Haber-Bosch process):
T= 500-600°C, P= 200-300 bars, catalysts Fe, mineral surfaces.
g. Hydrothermal conditions, Brandes [17] 1998:
T= 300-800°C, P= 1000 bars, catalyst Fe : for a ratio H2O/Fe = .5, production of 17% of NH3 at 700°C
T= 500°C, P= 1000 bars, catalyst Fe3O4 in HCO2H : production of 0.6% of NH3.
h. Hydrothermal conditions, Smirnov [18] 2008:
T= 200°C, P= 55 bars, catalyst Fe.
  • Polyphosphates.
i. Production of polyphosphates and their concentration by mineral surfaces.
Arrhenius [4] 1997:
Newbeyrite, Mg(OHPO3).3H2O gives oligo-phosphate up to 9 phosphates. Pressure 1 bar, heating of 100 to 550°C
also with brushite, Ca(OHPO3).2H2O and withlockite, HMgCa9(PO4)7.
  • Note on FTT process.

To illustrate the variety of products of FTT process here is the link to the American archives collected in Europe at the end of the 2nd World War that detail the various methods used and the various products obtained and their concentrations.
It is rare to find in the literature of olefins produced by FTT and whose double bond is in the middle of the chain. American archives above mentioned these olefins explaining the catalyst, Fe (CO) 5, would isomerize alpha-olefins by moving the double bond to the middle of the chain. Concentrations decrease with distance from the position of the double bond relative to the alpha carbon.
For U.S. archives you must start from wikipedia with "essence synthétique ", then click on "archive" in the section "Notes et références" for not to lose this link. In the american site surf as this: Government Reports (dans Primary Documents); U.S. Naval Technical Mission In Europe; Technical Report No.248-45 The Synthesis Of Hydrocarbons And Chemicals From CO And H2; olefines (page 81).

Working hypotheses for a pocket of abiotic oil.[edit]

   Given the profusion of H2 produced by the lithosphere: oceanic ridges, subduction zones and even in the pore waters of the rocks, you have to take into account in the quest for the origin of life, methane and oil abiotic that could be produced from H2 and CO2 serpentinization.
   We can consider three types of methane in the lithosphere according to their origin:

  1. The methane's serpentinization at pressures below 10 kbar and a temperature below 300 °C, in depth. The gas of clathrates identified in subduction zones should contain this methane.
  2. Biogenic methane from the surface, produced by methanogenic prokaryotes from biomass: Wisp, clathrates marshes, lakes, permafrost and continental shelves of the oceans.
  3. Abiotic methane produced at the upper mantle from carbonates and water at pressures greater than 50 kbar and at a temperature around 1500 °C. This methane was produced in the laboratory only (H.P Scott [19] & al., J.F Kenney [20] & al.). We could not, so far, show its existence in the field. It is supposed to become part of oil and up by faults or along plate subduction.

    I do not treat here the methane from the deep (type 3), because it concerns the abiotic oil controversy in the context of industrial production.

Oil from serpentinization[edit]

    What about the oil produced by the FTT process along serpentinization? At mid-ocean ridges, it is produced only in trace amounts, while the rate H2/CH4 may be very high. What becomes of this hydrogen? if it is not used for the synthesis of oil.

On the oceanic ridges sides:[edit]

diagenesis of clathrates of gas.[edit]

    An assumption made by specialists of ocean ridges, of whom J.L. Charlou Ifremer (Ifremer serpentinization and inorganic synthesis of hydrogen, methane and hydrocarbons along the Mid Atlantic ridge), is the formation of gas hydrates of methane trapped in sediments on the ridges sides. This methane would be produced directly by serpentinization by hydrothermal convection through the fractured crust. Let's develop a little, this hypothesis.

    First serpentinization does not produce methane, but produces H2 and produces or concentrate CO2 and N2. Methane production would done later by the FTT process. Serpentinization takes place between 50 and 300°C and at pressures up to 10 kbar. The gases produced by the sides are added to those already produced by the ridge. On sides, far from the axis, the fractures are less deep, the temperature lower and the pressure increases when descending. This allows the production of H 2 at a moderate temperature and promotes the formation of clathrates. Methane production by FTT could shrink faster than serpentinization, as it should be at a higher temperature (see McCollom [16]). But the more one moves away from the axis, the more sediment layer will thicken and the pressure will increase causing an increase in temperature by geothermal gradient.

    Take the example of the Tupi oilfield discovered off Brazil in a zone without subduction, under 2km of water and 5km of sediments. With a geothermal gradient of 30 °C/km and a pressure gradient of 250 bar/km in the sediments, we reach a temperature of 150°C, in which must be added heat supplied by the crust, and a pressure of about 1.5 kbar. Over millions of years these clathrates have been subjected to temperatures well below to 250°C of the optimum of the FTT process, and at pressures that will soon exceed 350 bars of the optimum, to achieve 1 to 2 kbar. Compared with the optimum, in that the hydrocarbon synthesis is exothermic, ( principe de Le Chatelier), equilibrium will be shifted to the methane with increasing pressure ( 4H2+CO2=CH4+2H2O ΔH=-151,3 kJ/mol; see dihydrogène for calculation); the drop in temperature will reduce the rate of the reaction but not the final equilibrium. The supercritical state of H2, CO2 and CH4 at these temperatures and pressures increases their reactivity, while the water and the long aliphatic chains are not in their supercritical state. With pressure all reactions are moving production chains longer and longer who find themselves increasingly in a non-critical condition. It should be added that trapping by long chains, the effect of surface clathrates/sediments mixture and the catalytic effect of transition metals.

   The interest of the hypothesis of JL Charlou, (Ifremer ), this is not so much the production of CH4 than H2 and the formation of clathrates. Studies of clathrates [21] [22] [23] are being very developed for the storage of hydrogen as an energy source, CO2 sequestration in the deep ocean and the release of methane by global warming. It is not a matter of developing it here, but these studies show that the conditions of temperature and pressure at the seafloor are compatible with the stability of the mixtures made of sediment and gas clathrates as those derived from serpentinization.

   At the same time the reduction of N2 to NH3 by H2 could be here similarly to CH4: supercritical gas reactants, exothermic reaction (3H2 + N2 = 2NH3 ΔH° = -92.2 kJ/mol) and thus movement of the equilibrium with the pressure. The industrial process Haber-Bosch at an elevated temperature (450 °C and 300 bar) and the absence of displacement by formation of long chains of nitrogen (as do the aliphatic chains) would leave suggest that in the conditions of abiotic oil pocket, NH3 does not form. However P. Avenier et al. 2007 [24] could produce NH3 from N2 and H2 at 250 °C and pressure of 1 bar as with tantalum silicate catalyst. It is entirely possible in the conditions of the pocket of abiotic oil with displacement of equilibrium by a pressure from 1 to 2 kbar. As for the quantities of NH3 produced it is not necessary that they be large, since its use will happen largely after the formation of liposomes that sequester NH3 (see Chapter metabolism initalisation lowest and the article on Prebiotic chimio-osmosis ).

   The release of phosphate from hydrogenphosphates by heat and its concentration by mineral surfaces (Arrhenius [4]) will be favored by the H2 (hydrogenation) but disadvantaged by the high pressure (precipitation), the temperature lower than 150 °C is still favorable as in the experiments Arrhenius.

   This diagenesis of clathrates hypothesis could explain, with tectonic plates, large deposits of oil and gas on the side of passive margins at great depth (Tupi), clathrates of gases having migrated to the subduction zones in accretionary prism, as well as shale gas by metamorphism of these mixed clathrates/sediments in the contact zone of two plates.

The zeolites[edit]

     Clathrates diagenesis resulted in the example of Tupi field poses a great mystery: the thickness of salt which is above is 3 km and there are 2 km of rocks still above. I also mentioned the use of zeolites for the industrial synthesis of abiotic oil in the study of the possibility of geochemical origin of the pocket prebiotic oil. Well zeolites are comprised of alumino-silicates or alumino-phosphates (AlPO4-type) whose blanks are initially occupied by cations (Ca Mg Na K ...) and water molecules and where can be carried catalysis.

    The question then arose: is that zeolites may be involved in geochemical processes on a large scale, in the synthesis of prebiotic oil? My interest in this issue has become essential when my curiosity was sharpened by reading an article on the description of salt concretions in the Afars rift in East Africa (Eitan Haddock, "La naissance d'un océan", 2009. Pour La Science No. 376 page 45). Yet E. Haddock clearly states hydrocarbon odors that emerge from these concretions. This geochemical index pushed me to do research on old rifts and I fell on the theory of parallelism between the geological oil deposits of Gabon and Brazil that occurred at the beginning of the separation of the two tectonic plates African and American. Now we are in the same situation as the Afars rift, but also with saline strata of few kms thick . It is tempting to answer yes to the question: it is possible that zeolites involved in geochemical level in the prebiotic synthesis of oil.

   But back to the diagenesis of gas clathrates we supposed to take place for the formation of prebiotic oil pocket. We calculated at Tupi, the depth below the seafloor led to temperatures around 150 °C and pressures around 2 kbar. These conditions are also those of the geological facies of zeolites: 50-150 °C and a depth below ground from 1 to 5 km. After diagenesis (first km) clathrates/sediments mixture, is what we do not start the zeolite facies? Then we will have closer clathrates and zeolites any two formed cavities, the first consisting of water cages trapping gases and the second, cavities promoting catalysis. From there to think that the pocket of prebiotic oil originates from these geological formations, there is only one step. But is it reasonable to propose such an abiotic model while all the works of oil exploration are in the theory of fossil petroleum and all are based on data measured in organic rocks attesting to their fossil origin? But is it unreasonable to consider the formation of abiotic oil when no life still exists? Is it unreasonable to equate the theoretical origin of abiotic oil with the formation of astronomical amounts of hydrocarbons on Titan, away from any photosynthesis in conditions of extreme cold? While we may one day prove that hydrocarbons of Titan are made by bacteria. But we will always be in the situation where the assumption pockets prebiotic oil remains plausible and, more, without the abundance of organic production due to photosynthesis. The situation on Earth is that the two processes, fossil and abiotic, can coexist at the same time and the fossil so pervasive that it would be difficult to demonstrate the existence of abiotic.

   Without going further into the controversy, it is clear that consideration of the combination of clathrates and zeolites enlightens us a new day on the assumption of prebiotic pocket oil and on the theory of fossil oil. Pocket fossil oil, we will see further interest to study the processes that take place in. These processes are conditioned by the high pressure therein, a few hundreds of bars, and by its gaseous environment and mineral. This is the situation that would exist of the molecular evolution of prebiotic pocket oil when the 1st beings appear and disappear zeolites, as in Tupi, staying only salt.

    For prebiotic pocket I had envisaged that the liposomes were formed from vesicles of water in oil (see prebiotic chemo-osmosis) allegedly migrated to the water phase incorporating the lipid second leaf. I invoked the formation of abiotic oil in porous rocks to increase the area of ​​catalysis, then migrating to the oil pocket. The mixture clathrates/zeolites seems more promising to me because we know that zeolites catalyze many reactions in organic chemistry, in addition to hydrocarbons (Khun P., thesis 2011, university of Strasbourg). Certainly the idea of ​​porous rock was adequate as I see it as for the fossil oil and the synthetic oil without zeolite, but its catalytic properties were limited to hydrocarbons. The products of the zeolite catalysis being very rich in various molecules would evolve more quickly the aqueous vesicles in oil. However, if the role of porous rock is limited and vague, zeolites are a big geochemical problem: how do they disappear, leaving only a thick layer of salt? For thick layers of underwater salt can not be explained solely by the evaporation process. It has been calculated that sea 1000 m depth would produce a layer of sel 16 m! (ocean salinity and density 3.5% salt at 25 °C, 2.17 g/cm³) It was also suggested process salt deposits by marine currents. But the origin of these immense layers by surface and thickness remain valid. Oil fields of the North Sea, Saudi Arabia, Brazilian odds, Venezuelan and Gabon are directly below a thick layer of salt (NaCl KCl CaSO4). Saliferous of Iran, on the surface, are close to oil fields as well.

  In conclusion the study of zeolites in the context of the prebiotic pocket oil convinces me strongly that everything is focused around its conditions of pressure and temperature: 150 °C and 2 kbar. These are:

  • Diagenesis clathrates,
  • since the beginning of geological zeolites facies,
  • the adaptation of bacteria to high pressures around 600 bar with simplification of their proteins (Badr Al Ali,2010 , page 10),
  • of organic chemistry reactions that occur more easily to these pressures while some can not even be carried out at standard conditions of a laboratory. It is called green chemistry [25].
  • the possibility that the prebiotic molecular evolution can take place under the same conditions of pressure and temperature in the depths of the seas of Titan and would explain the large quantities of hydrocarbons that are found.

At subduction zones: the transformation of methane to oil, in contact with hydrothermal fluids.[edit]

At subduction zones have been identified mainly gas clathrates that come from, in my opinion, as we saw earlier, from ridges by serpentinisation. We can always assume, for our abiotic pocket, a part of this abiotic methane is converted to oil in contact with hydrothermal fluids formed at high pressure and temperature along the subducting plates. The process FTT is initialized by steam reforming of methane, ammonia and phosphate being made ​​by hydrothemal fluids (see Chapters ammonia and phosphate above). The volcanoes subduction zones, finish their activity by a rejection of some hydrocarbons. But the area of ​​the subducting plate, between the accretionary prism of sediments and metamorphic zone of the volcanic arc, is very small in order to create large deposits of oil. For against this abiotic oil in small quantities locally, but spread over tens of thousands of miles, can be many opportunities to form favorable molecular evolution pockets.

Along transform faults:[edit]

Two examples of transform faults which I intend to study later: transforming plates between the Indian and Arabian plates and 2 transforming plates between the North American plate, Caribbean plate and South American plate in the Gulf of Mexico. What is interesting is that these faults have worked a long time for the rise of the Indian subcontinent to asia and the spacing of two americas which is the same time as the separation of the American continent of Africa. They could produce a very large amount of gas clathrates with methane and H2, which would explain the huge oil deposits in these areas: Gulf of Mexico and the Persian Gulf.

The working hypotheses for experimentation[edit]

The main points to be observed for testing the initialization of metabolism in the abiotic oil are:

  1. High pressure of the order of a few kbar at the beginning;
  2. A relatively low temperature, between 50 and 300 ° C;
  3. A powdered rock that will define which simulate a porous sedimentary deposit containing hydrogenphosphates and catalysts (Fe Ni and other elements to define according to the literature of industrial or experimental methods);
  4. Clathrate gas containing H2 reconstructed CO2 N2 H2O;
  5. H2S can block some reactions, it is also necessary to introduce gradually;
  6. If the product obtained is similar to the pocket of fossil oil can reduce the pressure and temperature in the following molecular evolution to identify if there is no initialization or metabolism.
  7. Priority to the synthesis of the oil first.
  8. Consider experiences long periods (or simulate) to reproduce geological time and the crystallization process.

Parallel with the theory of fossil petroleum[edit]

    While reading an article on the bacteria that cause problems in oil exploration I came across a diagram showing the interactions between the different species of prokaryotes that are found in a pocket of fossil petroleum and their environment (Dorota Wolickaa et al., 2010 [26]). This pattern, with gas and catalysts look like much to the result of a study on the pocket prebiotic oil. Thus:

  • These prokaryotes get their energy from mineral extraction and not of photosynthesis, such as prebiotic pocket;
  • consume small molecules of oil and gas. However ammonia and phosphate did not appear unlike the prebiotic pocket, because the phosphate is a limiting factor and certain species rapidly converted ammonia nitrate which is in turn used by other species for energy and manufacturing amino acids;
  • aqueous vesicles can form in the oil phase and liposomes in water phase, and we are then in the same situation as in the prebiotic pocket for prebiotic molecular evolution ;
  • Pressure conditions, and to a lesser extent temperature conditions, force prokaryotes to adapt to meet the conditions required for the initialization of molecular evolution. Thus we see that at high pressures, around 600 bars, prokaryotes simplify their proteins that become monomeric instead of staying multimeric, as aliphatic chains lengthen and increase the number of unsaturated bonds. (Badr Al Ali,2010 , page 9).
  • We then find ourselves in a situation where we can no longer distinguish whether the prokaryote has reached the maximum regression can still be defined as living or if the liposome formed in the fossil pocket and having undergone prebiotic molecular evolution, reached a maximum stage of development so that it passes for a living. It is at this level that poses the riddle procayotes endemic pockets of fossil petroleum: are they born in oil or has not yet been able to demonstrate their foreign-born origin [27]?

    Pocket fossil oil has the advantage to exist, many experiments have been made to solve oilfield problems. These experiments have developed the techniques of high pressure and extreme temperature conditions. However, they were not made ​​in the context of the prebiotic molecular evolution. They could be applied to the pocket prebiotic oil. In particular it would be wise to experiment with a fossil pocket without prokaryotes with phosphate, ammonia, some amino-acids and nucleic bases to observe molecular evolution at an advanced stage. But already in the literature can be studied, always in the context of the prebiotic molecular evolution, interactions between the surrounding environment and the metabolism of prokaryotes in fossil pocket.

Initialization metabolism in the pockets of abiotic oil similar to those of fossil petroleum[edit]

   I do not imagine metabolism in an open environment, not confined in a small volume of the cell size. Whatever the network of chemical reactions, which stood at a given moment in an open environment, it is automatically destroyed by the process of diffusion. Well delimited by a closed lipid wall network will not communicate with the outside and so will not change.

   Many experiments have been made with mineral surfaces, so open environments, in order to demonstrate the catalyst and / or the concentration of organic or inorganic molecules such as phosphates, amino acids and nucleic acids. But none of them was available to suggest an initialization metabolism unless imagining complex scenarios involving multiple processes at once, as the alternation of hot and cold, dryness and moisture, day and night, light processes etc ...

   Two experiments were carried out to confine the metabolism in a liposome. And in both cases the need to communicate with the outside appears paramount. Deamer [28] et al. (2002), experiment in the model of the "RNA world", encapsulating the RNA in liposomes made of aliphatic chains of 14 carbons, for that the membrane is permeable enough to let pass the nucleotides. Davis [29] et al. (2009) will make a minimal artificial cell capable of communicating with the outside. They demonstrate that the encapsulation necessary for the reaction ingredients can produce formose sugars including pentoses. But they were forced to insert into the membrane a bacterial protein, α-hemolysin, which self-assembles into a pore to get sugars and thus communicate with the outside.

   In what follows we will show that the metabolism can be initialized through the lipid bilayer with primitive pores that allow interaction with the external environment. Whether it be a specific part metabolism, confined within the liposome, which corresponds to the classical notion of metabolism, and a membrane portion that serves as communication interface. For this we will first present the state of research on the abiotic synthesis of phospholipids as I did for the abiotic oil.

Research status on the abiotic synthesis of phospholipids and small molecules[edit]

   We have seen for the introduction of the pocket prebiotic, in geochemical terms and taking into account that the NPS elements must be present, that any organic molecule may be synthesized under the conditions of temperature and pressure (and with geological periods) in this pocket. However, while for the oil abiotic strictly speaking in the absence of NPS (with production of fatty acids, alcohols, aldehydes, aliphatic chains, olefins, cycles and hetero-cycles with oxygen) we have the example of the industrial synthesis and 1st geochemical indexes with hydrothermal vents, to the hydrophilic head of phospholipids, ie glycerol and ethanolmine (phosphate is assumed to exist from the point of view geochemical), we have only examples of industrial and laboratory syntheses.

   To achieve some necessary steps in the synthesis of phospholipids I established in Table 3 a list of reactions used by laboratories and industry. It should be noted however, that even if industrially produced small molecules of glycerol and ethanolamine, and there are some laboratory experiments to synthesize phospholipids, we currently continue to use natural phospholipids for biological or medical experiments because that easy to extract them from natural organic products.

   Table 3. Industrial and laboratory processes for the synthesis of phospholipids and their components

  • 1 - Fatty acids esterification  :
  • The esterification is an athermal reaction, with an acid or a base as catalyst; maximum yield, several months without catalyst. ( Esterification )
  • Hydrothermal conditions between 100 et 300 °C. ( Rushdi [30] et al. 2006 )
2 fatty acids + glycerol ---> diacyl-glycerol (1,2/1,3 = 1)
7C, 2% on average and to 11% with H2 (a. oxalique) and 100 °C ; over than 34% of mono-acyl beyond 200 °C. during 72h.
fatty acid + ethylene-glycol ---> acyl-ethylene-glycol 19C, 50% on average to 250 °C. during 72h.
Self-assembly to bilayer ( without phosphate and ethanolamine).
  • 2 - Ethoxide : CH2=CH2 ethylene, synthesized by FTT
  • CH2 = CH2 + Cl2 + H2O ---> CH2Cl-OHCH2 + HCl ethylene chlorohydrine ( Weissermel [31] et al. 2003, p 146)
  • 2( CH2Cl-OHCH2 ) + Ca(OH)2 ---> 2 (CH2CH2)O + CaCl2 + 2 H2O Ethoxide (same reactions as propene : see glycerol)
  • 3 - Ethanolamine
  • (CH2CH2)O + NH3 ---> OH-CH2CH2-NH2 (Weissermel et al. 2003, p 159)
solution 20-30% NH3, 60-150 °C, 30-150 bars. (mono+di+tri) Ethanolamine
  • HOCH2CHO + NH3 ---> (OH-CH2CH=NH) + H2O (imine, amination, glycolaldehyde) A.D.Aubrey et al. (2009), Fig 4 [32]
(OH-CH2CH=NH) + H2 ---> OH-CH2CH2-NH2 Ethanolamine
Hydrothermal conditions, 50-300°C et 200 bars; 0.1 to 0.001M/kg de NH4HCO2.
  • 4 - Esters phosphates
  • Ethanolamine + H3PO4 ---> Ethanolamine-H2PO4 + H2O 185 °C, 1 bar ( orgprepdaily )
  • Glycerol + H3PO4 ---> Glycerol- H2PO4 + H2O (rac : 1 et 3) (rac : 1 et 3) 105 °C, 1 bar (J.J Rae [33] et al. 1934, p. 143)
  • 5 - Hydroformylation: ( Györgydeák [34] et al. 1998)
  • CH2O + H2 + CO ---> Glycolaldehyde, Glyceraldehyde, sugars with 4 5 6 C.
140 °C, 120 bars, catalyst: Co+triethylamine
150-220 °C, 1 bar, catalyst: Ni on Si or Al
250 °C, 50-100 bars, catalyst : Cu, ZnO, Al2O3. This is like FTT.
FTT produces short chain molecules when the temperature is higher than the optimum. McCollom [16] 1999 p.156.
650 °C, 1 bar, catalyst : Ag
  • 3 CH3OH + K2Cr2O7 + 8 HClO4 ---> 3 CH2O + Cr2(ClO4)6 + 2 KClO4 + 7 H2O ( E. Pérez-Benito et al. 1993 [35] )
instead of HClO4 one can use H2SO4, chemical solution 25 °C, 1 bar.
chemical solution 25 °C, 1 bar, acid solution :H2SO4
  • CH3CHO + HCN ---> CH3CH2OCN    lactonitrile, basic catalyst, 1 bar; puis
CH3CHOHCN + 2H2O ---> CH3CHOHCO2H    lactic acid, H2SO4, 100 °C, 1 bar. ( Weissermel [31] et al. 2003, p 305)
  • 6 - Sucres phosphates: TMP, Trimetaphosphate
  • Glyceric acid + TMP ---> 2-Glycerate-P + 3-Glycerate-P alcalin solution; ( Orgel [36] et al. 1996)
  • NH3 + TMP ---> NH2-(PO3)3 ( Orgel [37] 2004 )
  • Glycolaldehyde + NH2-(PO3)3 ---> Glycolaldehyde-P Mg++ pH 7 ( Eschenmoser [38] et al. 1999)
  • R-CHOH-CHO + NH2-(PO3)3 ---> R-CHOPO3-CHO 27 aldéhyde-2-P ( Orgel [37] 2004 )
  • 7 - Glycerol: CH2=CHCH3 propene, synthesized by FTT
  • CH2 = CHCH3 + Cl2 ---> CH2 = CHCH2Cl + HCl ( Weissermel [31] et al. 2003, p 296)
from 300 °C, 85% yield at 500-510 °C, 1 bar ; Allyl chloride
  • CH2 = CHCH2Cl + HOCl ---> CH2Cl-OHCHCH2Cl + CH2OH-ClCHCH2Cl (p 297)
aqueous phase, 25-30 °C, hypochlorate, dichlorohydroxypropane 70%, 30% respectively
  • 2 CH2Cl-OHCHCH2Cl + Ca(OH)2 ---> 2( CH2 =O= CHCH2Cl ) + CaCl2 + 2 H2O (p 297)
50-90 °C epichlorhydrine
  • ( CH2 =O= CHCH2Cl ) + H2O ---> OHCH2-OHCH-CH2Cl (p 302)
OHCH2-OHCH-CH2Cl + H2O ---> OHCH2-OHCH-CH2OH + HCl   glycerol
in chemical solution 10% caustic soda, 100-200 °C, high pressure.
Ni, 60 bars of H2. 50 °C.
  • Note on the other abiotic molecules needed to metabolism initialization:
   Table 3 was designed initially for the synthesis of phospholipids alone but incorporates lactic acid also because I stopped writing "prebiotic petroleum" for "prebiotic chemo-osmosis" with the assumption that ionophores prefigured the prebiotics pores and could solve the problem of communication of the liposome with its environment as I mentioned in the introduction to this chapter. Ionophores are in "prebiotic chemo-osmosis" in first chapiter.
It should be added to this table abiotic synthesis of amino acids and nucleic bases, and the study of their stability in hydrothermal conditions.
  • Amino acids:
HCOO-NH4+ <----> HCONH2 + H2O (amination, formic acid) A.D.Aubrey et al. (2009), Fig 3 [39]
HCONH2 <----> H2O + HCN -------> Gly DL-{Ser Ala Asp Glu} ( cyanidric acid, racemic amino acids )
Hydrothermal conditions, 50-300 °C and 200 bars; 0.1 à 0.001M/kg de NH4HCO2.
Experience has also studied the stability of these amino acids (Figure 5). Formic acid is believed to be produced like other fatty acids by the FTT process ( see equation of FTT in table 2).
  • Nucleobases:
   Many studies suggest 5 HCN condensation to form an adenine molecule as origin of prebiotic adenine. Article AD Aubrey above does not mention it. The hydrocyanic acid may come from the acid decomposition of the [w: Ferrocyanure_de_potassium|potassium ferrocyanide]], which is found in the sediment. Michael Franiatte (2008) [40] showed the stability of adenine in hydrothermal conditions.
  • Other abiotic molecules:
   Other abiotic molecules involved in the steps of initializing the metabolism here and in the other 2 articles (prebiotic chemo-osmosis and prebiotic chirality) are assumed to exist as I mentioned in the introduction to the properties and geological evolution of the pocket prebiotic oil.

  • Note on the problem of abiotic synthesis of glycerol.

   The industrial synthesis of glycerol from propene, component of fossil petroleum or synthetic oil, exists (see paragraph 7 of Table 3). Only the method used is very drastic and does not correspond to biological processes even under hydrothermal conditions: use of Cl2, HOCl, Ca (OH) 2, caustic soda, metal catalysts, high pressures and high temperatures. When the hydrogenation of glyceraldehyde it is made at high pressure of gas H2. Glycerol does not appear in the hydroformylation synthesis (paragraph 5) or in the formose reaction which are in aqueous phases and under near hydrothermal vents and produce glyceraldehyde and sugars, while H2 is present. So it does not appear with ethanolamine and amino acids under hydrothermal conditions in the presence of NH3 and H2 (see paragraph 3 of ethanolamine).

   Even if we assume that glycerol is produced in small quantities in the pocket of prebiotic oil, as I expressed earlier in this article, it would be difficult to move the reaction equilibrium by trapping on or in the liposome. So unless we assume that the prebiotic oil is produced under extreme conditions as I assumed in subduction zones should be as glycerol is produced at the same time and in large quantities, as many as half of fatty acids to form the head of the phospholipid and it should not be degraded. This situation seems implausible, no geochemical petroleum research or outside does not mention it.

   It is to these difficulties to synthesize hydrophilic head of phospholipids and the belief that I have posted in the introduction to this chapter that molecular evolution can only be done in a closed system, that I have undertaken in the first instance to study the properties of liposomes before understanding their synthesis. This is how I wrote the first article on chemo-osmosis. It is clear to me that the electrical potential established between the two leaflets of the bilayer should be the engine of molecular evolution. I tried with "prebiotic chemo-osmosis" to also propose a scheme of metabolism initialization and the synthesis of hydrophilic heads but this is in the second article "prebiotic chirality" where I developed consistently this metabolism initialization based on the mechanical cohesion of the liposome instead of the electric potential process. The 2 processes remaining complementary to the dynamic evolution of the liposome.

   It is important to note the writing dates of these articles for reflection and bibliographic research evolve and contradictions and inconsistencies between these articles can occur. As well as certain assumptions may be unfounded. I use to this discussion topic of Wikiversity to rectify.

   I started to write this article about the prebiotic oil quite early in my work. I had stopped at the table 3 for the reasons I mentioned to go to the writing of prebiotic chemo-osmosis. So thinking about the initialization of metabolism that I start there in this chapter comes after the writing on this subject in the two preceding articles and even after the research I have done then to conceptualize molecular evolution and evolution as a whole in continuity with Darwinian evolution. An article on the concept of molecular evolution is being written. What I describe in the following subchapter is the consolidation of all my research done so far on the initialization of metabolism by describing the early stages of molecular evolution.

The initialization processes of metabolism[edit]

   Initialization metabolic processes in the prebiotic oil may begin then, according to the hypothesis of confinement that I just mentioned, as soon as aqueous vesicles formed in the oil. It will then continue in the liposomes. According to the geological processes involved in the formation of prebiotic oil, by formation and diagenesis of clathrate gas at oceanic ridges or in the ascent of hydrothermal fluids along the subducted plates, physico-chemical processes that produce oil and hydrophilic molecules required for metabolic initialization will be different. It is only experimentation and field measurements that will decide, but already we can differentiate the two processes by their duration.

   The extreme conditions of hydrothermal fluids resemble industrial processes and seem to favor the production of NH3 by the Haber-Bosch process, the phosphate from apatite, that of HCN from CH4 and NH3 directly, and the oil by industrial processes FTT in extreme conditions. This production is fast and produces good water/oil emulsion due to the strong flow of fluids. But it poses a problem for some molecules such as CO and HCN issue very short-lived and may disappear quickly not allowing the renewal of small molecules from the hydroformylation (glyceraldehyde, DHA, glycolaldehyde) and amination (amino acids, ethanolamine, nucleic bases) which are more or less unstable especially in the extreme conditions of hydrothermal fluids.

   Against by diagenetic processes, as I detailed in the chapter on clathrates occur on geological times and can produce prebiotic soup continuously through a process of drip falling from the porous rock of clathrates/sediments in the oil phase already formed in the oil pocket.

   In the prebiotic soup before initialization metabolism in aqueous vesicles, we will find different products made by geochemical processes encountered so far and that can be classified as following:

  • primary geochemical processes such as serpentinization producing gas H2 CO2 CH4 N2 H2S, sedimentation producing hydrogenphosphates for diagenesis and percolation producing free phosphate for hydrothermal fluids.
  • Secondary geochemical processes during the ascent of hydrothermal fluids or diagenesis clathrates and using primary products. These processes use primarily catalysis mineral surfaces and high pressures and temperatures. These are:
  • The process of FTT, H2 + CO, giving long chain of alcohols, fatty acids, olefins, and small molecules of formaldehyde, acetaldehyde and especially formic acid (see equation FTT Table 2).
  • The Haber-Bosch process, N2 + H2, to give NH3.
  • Release by the heat and acidity, phosphates from hydrogénophosphastes and HCN from ferrocyanide.
  • Tertiary processes, chemical processes, using products of secondary processes and may occur in water, ie the prebiotic soup. These are:
  • The hydroformylation or formose reaction using formaldehyde + H2, and giving glyceraldehyde, glycolaldehyde and DHA.
  • The amination using formic acid + NH3 to give Gly Ser Ala Glu Asp and ethanolamine but also HCN and nucleic bases.
  • The synthesis of nucleic bases from HCN released from ferrocyanide.
  • and finally phospho-esterification of glyceraldehyde, glycolaldehyde, DHA, ethanolamine and Ser.

Initialization metabolism in the aqueous vesicles of oil phase[edit]

But also in the interface water/oil of the 2 main phases. Four important processes run this initialization:

  • Catalysis by the multi-anionic surface of the vesicle, the hydrogenation of Glyceraldehyde-P or P-DHA to glycerol-3P after fixing them on the fatty acid. Hydrogenation made ​​possible by the presence of H2 (see more detail Prebiotic chirality Sub-Chapter 2, Section 4).
  • The movement of chemical equilibria of prebiotic soup after the formation of the hydrophilic head.
  • The esterification is the main engine displacement of chemical equilibria because it is a reversible reaction and athermal. The catalysis can be acidic or basic. Any process that traps the reactants moves its thermodynamic equilibrium. It should be noted that the majority of enzyme esterifications are directional so that the chemical reaction without enzyme is reversible. This is the main function of these enzymes. Initialization metabolism continues with the esterification of serine or ethanolamine or glycerol to the fixed arm of the phospholipid.
  • Intercalation of hydrophobic molecules between fatty acids having in the interface water/oil of the vesicle chemical function other than the carboxylic function. This is the case of nucleic bases, but also hydroqinones. For nucleobases, forming the glycosidic bond with N of the base can be done first with the glyceraldehyde-P aided by the multi-ionic vesicle surface as to form the hydrophilic head, but without hydrogenation. Then add this product to a molecule of acetaldehyde to form a deoxy-glycoside (dRN) or a molecule of glycolaldehyde to form a glycoside (RN). DHA-P can take the place of glyceraldehyde-P after isomerization. These glycoside bonds are more difficult than the ester bonds. But the synthesis of saccharides is not a priority at this stage of initialization metabolism. Similarity can be compared synthesis of Thr (Gly + acetaldehyde) inside the vesicle to the formation of dR.

   Initialization metabolism is limited by the availability of basic products including H2 as aqueous vesicles in the oil phase does not communicate with each other even by passive diffusion. Also there would be some vesicles that could turn into liposome the other would discharge their contents in the water phase and their phospholipids would fit in the main interface water/oil that will serve as the second sheet to the strongest vesicles to form a liposome which detach in the water phase.

Liposome formation[edit]

Passage of aqueous vesicles of the oil phase to the water phase covering with second sheet of phopholipids.
By gravity, water is heavier than oil, aqueous vesicles go down to the water phase and get in touch with oil/water interface of the two main phases. This interface consists of phopholipids of aborted vesicles as we have seen in the previous paragraph. Pressure of vesicles accumulated on the interface forces solid vesicles to detach from the interface covering with second sheet of phopholipids. Liposomes are then formed.

Importance of liposomes in the initialization metabolism[edit]

Five major roles in the initialization of metabolism are the responsibility of the liposomes.

  • The interior can now communicate with the outside by passive diffusion and bring most small molecules of prebiotic soup that spilled into the water phase after abortion of less robust vesicles. Initialization can thus continue except with phosphate, ions, and some large molecules and strongly polar molecules which require pore exchange.
  • The mechanical cohesion of liposome accelerates the formation of phospholipids (see more detail Prebiotic chemio-osmosis ).
  • Zwitterionic hydrophilic heads such as amino acids will trap any amino acid even more difficult to synthesize but can be found in the prebiotic soup according to the principle stated at the beginning of this article that any chemical reaction can take place over time in the pocket prebiotic oil. Including aliphatic amino acids and Thr we have seen in paragraph of aqueous vesicles. Moreover, the reaction we mentioned for the Thr may be done in the prebiotic soup before vesicle formation. These amino acids can form pores as discussed in the last role of the liposomes.
  • The chemical reaction space is now differentiated in 5 zones by the liposome instead of 2 zones in aqueous vesicles.

The five zones of the interior to the exterior of the liposome, are (see more detail in Prebiotic chemio-osmosis ):

  1. the center
  2. The inner wall of the bilayer (first sheet)
  3. Area aliphatic tails of the 2 sheets
  4. The outer wall of the bilayer (second sheet)
  5. The outside close to the wall
  • Establishment of chemo-osmosis and pore formation.

The chemical differentiation between inside and outside cause temporarily and time to time electric potential because ions come up to external surface, as in chemo-biotic osmosis. Amino acids hung on the outer wall of the bilayer by ionic loose bonds, hydrogen bonds or weak bonds by Van Der Walls force for hydrophobic groups tend to sink into the bilayer to reduce the electrical potential. In the article by prebiotic chemo-osmosis I involve alpha-hydroxy acids such as lactic acid, which can establish ester bonds between themselves or with the alpha-amino acids, bonds that we have seen in the formation of hydrophilic heads are very adapted for initializing the metabolism. This idea comes from the observation that prokaryotes use small cyclic molecules consisting of some alpha-hydroxy or amino acid monomers and serve as ionophores such as ion exchange channels. Just can one ionophore exchange ions, even very slightly, so that the prebiotic molecular evolution can continue and liposome become functional, and can interact with its environment. ( see more detail in Prebiotic chemio-osmosis ).

The future of research on prebiotic oil[edit]

The search stops with geochemical processes. Indeed the geological and geochemical processes, especially with the composition of the prebiotic soup, even define the meaning of "origin of life" because beyond our control or any hypothesis. We can experience our assumptions about molecular evolution laboratory with the liposomes, but the initial conditions must be those of the pocket prebiotic oil discovery even if we could repeat the experience.
The different research directions, always with a view of the origin of life and therefore of the formation of pockets of prebiotic oil, are:

  • On passive margins
  1. The formation and diagenesis of clathrates/sediments mixture
  2. The formation of saliferous strata and zeolites on the ocean floor
  3. Study rifts, their oil and volcanoes of carbonatites accompanying
  4. Experimental diagenesis of clathrates/sediments mixture
  • On subduction zones
  1. Study of gas clathrates in accretionary prism
  2. Study of hydrothermal fluids
  3. Organic ejections of volcanoes in subduction zones
  • The transforming plates: Produce they clathrates gas?
  • The pocket fossil petroleum

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