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The composition of the substance under consideration in a modular scheme (Fig. 1) in the C–H–O phase diagram. (a and b) Using the chemical potentials of CH 4 and H 2 , a twoocomponent system C–O is formed; (c) the use of the chemical potential of CO 2 leads to the C–H system. Phosphorylated compounds are represented by the subtraction of orthophosphoric acid (H 3 PO 4 ). The substances of C–H–O systems are represented by solid triangles; the C–H–O–P system is shown using clear squares. Compounds: (1) fumarate (Fum), (2) succinate (Suc), (3) acetate (Ac), (4) pyruvate (Pyr), (5) malate (Mal), (6) glyoxx ylate (Glx), (7) oxaloacetate (Oxal), (8) phosphoenolpyruvate (PEP), (9) 33phosphoglycerate (PG), (10) glyceraldehyde phoss phate (GAP), (11) fructosee66phosphate, (12) ribulosee1,55bisphosphate, and (13) fructosee1,66biphosphate (FBP).
Source publication
According to J.W. Gibbs, the number of independent components is the smallest number of those chemical components whose combination yields the compositions of all possible phases of a system; at the first stages of the development of the primary metabolism of a three-component C–H–O system, the source of energy for it consists of various hydrocarbo...
Contexts in source publication
Context 1
... addition of phosphoo rus to the system generates a fourrcomponent system of C-H-O-P; the independent components carbon, hydrogen, oxygen, and phosphorous are extensive parameters (f ex ). Figure 2 demonstrates the phase diagrams of the compositions of the compounds that are given in Fig. 1. In this threeecomponent diagram, the C-H-O phases of phosphorylated compounds are presented by subtracting of the phosphoric acid (H 3 PO 4 ) composii tion. ...
Context 2
... is used in the calculation (transition of methane and hydrogen into intensive parameters (f in )), the threeecomponent system is transformed into a twoocomponent system of C-O (Figs. 2a and 2b). The dashed conodes link CH 4 and H 2 with the phases of acids, which are indicated by asterisks and rhombs on the sides of the triangles. It follows from the diaa gram of compositions ( Fig. 2c) that in the use of the chemical potential of CO 2 ...
Context 3
... of methane and hydrogen into intensive parameters (f in )), the threeecomponent system is transformed into a twoocomponent system of C-O (Figs. 2a and 2b). The dashed conodes link CH 4 and H 2 with the phases of acids, which are indicated by asterisks and rhombs on the sides of the triangles. It follows from the diaa gram of compositions ( Fig. 2c) that in the use of the chemical potential of CO 2 ...
Context 4
... and H 3 PO 4 ( ) on the formation and development of the coupled C-H-O-P metabolism systems that were presented in Fig. 1. In this twoocomm ponent C-O system (Fig. 2a), according to the Gibbs phase rule, the points in the diagram are fourrcompoo nent nonvariant equilibria, while univariant equilibria are threeephase, separating the divariant fields of phase stability and their parageneses, which are signii fied by linear diagrams in the facies of the ...
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In theories of the origin of life, the most reasonable is the concept of the primacy of autotrophic metabolism, in which carbon dioxide (CO2) is considered as the only source of carbon for the functioning of nascent metabolic pathways. The aim of this paper was to demonstrate that the origin and development of primary autotrophic metabolism on early Earth were influenced by the two different regimes of degassing of the Earth-reducing (predominance CH4) and oxidative (CO2). It follows from this that the ancestral carbon used in metabolism may have been derived from CH4 if the outflow of magma fluid to the surface of the Earth consisted mainly of methane. In such an environment, the primary autotrophic metabolic systems had to be methanotrophic. Due to the absence of molecular oxygen in the Archean conditions, this metabolism would have been anaerobic, i.e., oxidation of methane should have been carried out by inorganic high-potential electron acceptors. In light of the primacy and prevalence of CH4-dependent metabolism in hydrothermal systems of the ancient Earth, we propose a model of carbon fixation where the methane is fixed/transformed in a sequence of reactions in an autocatalytic methane-fumarate cycle. Nitrogen oxides are thermodynamically most favorable among possible oxidants of methane; however, even the activity of oxygen created by mineral buffers of iron in hydrothermal conditions is sufficient for methanotrophic acetogenesis. The Hadean-Archaean hydrothermal system model is considered in the form of a phase diagram, which demonstrates the area of redox and P, T conditions favorable for the formation and development of primary methanotrophic metabolism.
The origin and development of the primary autotrophic metabolism on early Earth were influenced by the two main regimes of degassing of the Earth – reducing (predominance CH4) and oxidative (CO2). Among the existing theories of the autotrophic origin of life in hydrothermal environments, CO2 is usually considered to be the carbon source for nascent autotrophic metabolism. However, the ancestral carbon used in metabolism may have been derived from CH4 if the outflow of magma fluid to the surface of the Earth consisted mainly of methane. In such an environment, the primary autotrophic metabolic systems had to be methanotrophic. Due to the absence of molecular oxygen in the Archean conditions, this metabolism would have been anaerobic; i.e., oxidation of methane must be realized by inorganic high-potential electron acceptors. In light of the primacy and prevalence of CH4-dependent metabolism in hydrothermal systems of the ancient Earth, we propose a model of carbon fixation where the methane is fixed or transformed in a sequence of reactions in an autocatalytic methane–fumarate cycle. Nitrogen oxides are thermodynamically the most favorable among possible oxidants of methane; however, even the activity of oxygen created by mineral buffers of iron in hydrothermal conditions is sufficient for methanotrophic acetogenesis. The hydrothermal system model is considered in the form of a phase diagram, which demonstrates the area of redox and P and T conditions favorable for the development of the primary methanotrophic metabolism.
Strategies for the origin and development of primary metabolism on early Earth were determined by the two main regimes of degassing of Earth in the form of CO2 or CH4 fluid impulses. Among the existing theories of the autotrophic origin of the life, CO2 is usually considered the carbon source for nascent autotrophic metabolism. However, the ancestral carbon used in metabolism may have been derived from CH4 if the outflow of magma fluid to the surface of the Earth consisted mainly of methane. Primary biochemical systems are present in methane degassing regimes developed in an environment of high partial pressure of methane, which is a source of carbon for nascent metabolic systems. Due to the absence of molecular oxygen in the Archaean conditions, this metabolism would have been anaerobic, i.e., oxidation of methane must be realized by inorganic high-potential electron acceptors. In light of the primacy and predominance of CH4-dependent metabolism in hydrothermal systems of the ancient Earth, we propose a model of carbon fixation, which is a sequence of reactions in a hypothetical methane-fumarate (MF) cycle. Thermodynamics calculations showed a high efficiency of oxidation of methane to acetate (methanotrophic acetogenesis) by oxidized nitrogen compounds in hydrothermal systems. Thermodynamically favorable were also reactions involving the introduction of carbon methane into the intermediates of the proposed MF cycle. The methane oxidation reactions with the use of oxygen of iron mineral buffers are closer to the equilibrium state, which apparently determines the possibilities of primordial cycle flow in the forward or reverse directions.
