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![Cysteine, cystine, and thiolate. The pKa for unperturbed CYS is about 8.25 (Matsui et al. 2020). It is obtained from the equilibrium constant Ka for the reaction CysSH ↔ CysS⁻ + H⁺ with Ka = [H⁺][CysS⁻]/[CysSH] and pKa = − log Ka in which the equilibrium concentrations of participants are given in mol/l. The redox potential is gained for the reaction shown in the figure according to the following equation ε’ = ε’o − (RT/nF) ln([reduced form]/[oxidized form]), where T is the temperature measured in Kelvin (K) degrees, R is the universal gas constant (8.314 J K⁻¹ mol ⁻¹), F is the Faraday constant, and n is the number of transferred electrons which is two for CYS reaction. The ε′o = − 220 mV (Jocelyn 1967). The ionization of neither the amine groups nor the carboxyl groups is shown in the figure](publication/355803502/figure/fig3/AS:1085198640906249@1635742926932/Cysteine-cystine-and-thiolate-The-pKa-for-unperturbed-CYS-is-about-825-Matsui-et-al.png)
Cysteine, cystine, and thiolate. The pKa for unperturbed CYS is about 8.25 (Matsui et al. 2020). It is obtained from the equilibrium constant Ka for the reaction CysSH ↔ CysS⁻ + H⁺ with Ka = [H⁺][CysS⁻]/[CysSH] and pKa = − log Ka in which the equilibrium concentrations of participants are given in mol/l. The redox potential is gained for the reaction shown in the figure according to the following equation ε’ = ε’o − (RT/nF) ln([reduced form]/[oxidized form]), where T is the temperature measured in Kelvin (K) degrees, R is the universal gas constant (8.314 J K⁻¹ mol ⁻¹), F is the Faraday constant, and n is the number of transferred electrons which is two for CYS reaction. The ε′o = − 220 mV (Jocelyn 1967). The ionization of neither the amine groups nor the carboxyl groups is shown in the figure
Source publication
In the chemoautotrophic theory for the origin of life, offered as an alternative to broth theory, the archaic reductive citric acid cycle operating without enzymes is in the center. The non-enzymatic (methyl)glyoxalase pathway has been suggested to be the anaplerotic route for the reductive citric acid cycle. In the recent years, much has been lear...
Citations
... Recently, an oxido-reduction approach fitting to chemoautotrophic origin of life and implying the role of MGO in triose formation was presented [25]. Taking MGO as raw molecule, glycerol, glyceric acid, and tartronic acid were identified as endproducts parallel to the role of LAC. ...
... Taking MGO as raw molecule, glycerol, glyceric acid, and tartronic acid were identified as endproducts parallel to the role of LAC. A simplified network was deduced involving all trioses playing crucial role in extant metabolism (Fig. 3A) [25]. Intriguing feature of the set of these compounds is that at the present status of knowledge almost all compounds exist in phosphorylated form, too (Fig. 3 B). ...
... The proposed route was suggested as the anaplerotic pathway to the rTCA in the conjunction with the surface metabolism theory, which in its larval form was already an initiative for the later developed glycolysis without phosphorylated intermediates [24]. In the second stage, a simplified network deduced from the oxido-reduction network of MGO was used (Fig. 3A, [25]). If other reactions, such as aldolization, hydration, and keto-enol tautomerism, are also taken into account, it becomes obvious how large set of compounds can be created. ...
Glycolysis is present in nearly all organisms alive today. This article proposes an evolutionary trajectory for the development of glycolysis in the framework of the chemoautotrophic theory for the origin of life. In the proposal, trioses and triose‐phosphates were appointed to starting points. The six‐carbon and the three‐carbon intermediates developed in the direction of gluconeogenesis and glycolysis, respectively, differing from the from‐bottom‐to‐up development of enzymatic glycolysis. The examination of enzymatic reaction mechanisms revealed that the enzymes incorporated chemical mechanisms of the non‐enzymatic stage, making possible to identify kinship between glyoxalases and glyceraldehyde 3‐phosphate dehydrogenase as well as methylglyoxal synthase and triose‐phosphate isomerase. This developmental trajectory may shed light on how glycolysis might have developed in the non‐enzymatic era. This study stresses that the development of glycolysis/gluconeogenesis started at the level of trioses originating from the formose cycle in the non‐enzymatic era of evolution. The six‐carbon and the three‐carbon intermediates developed in the direction of gluconeogenesis and glycolysis, respectively. The chemical reactions of the non‐enzymatic era are present in the depths of contemporary enzymatic functions, allowing the understanding of evolution.
