Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, China.
Astrobiology. 2011 Jun;11(5):471-6. doi: 10.1089/ast.2011.0624.
The iron-sulfur world (ISW) theory is an intriguing prediction regarding the origin of life on early Earth. It hypothesizes that life arose as a geochemical process from inorganic starting materials on the surface of sulfide minerals in the vicinity of deep-sea hot springs. During the last two decades, many experimental studies have been carried out on this topic, and some interesting results have been achieved. Among them, however, the processes of carbon/nitrogen fixation and biomolecular assembly on the mineral surface have received an inordinate amount of attention. To the present, an abiotic model for the oxidation-reduction of intermediates participating in metabolic pathways has been ignored. We examined the oxidation-reduction effect of a prebiotic FeS/S/FeS(2) redox system on the interconversion between several pairs of α-hydroxy acids and α-keto acids (i.e., lactate/pyruvate, malate/oxaloacetate, and glycolate/glyoxylate). We found that, in the absence of FeS, elemental sulfur (S) oxidized α-hydroxy acids to form corresponding keto acids only at a temperature higher than its melting point (113°C); in the presence of FeS, such reactions occurred more efficiently through a coupled reaction mechanism, even at a temperature below the phase transition point of S. On the other hand, FeS was shown to have the capacity to reversibly reduce the keto acids. Such an oxidoreductase-like chemistry of the FeS/S/FeS(2) redox system suggests that it can determine the redox homeostasis of metabolic intermediates in the early evolutionary phase of life. The results provide a possible pathway for the development of primordial redox biochemistry in the iron-sulfur world. Key Words: Iron-sulfur world-FeS/S/FeS(2) redox system-Oxidoreductase-like chemistry. Astrobiology 11, 471-476.
铁-硫世界（ISW）理论是一个关于早期地球上生命起源的有趣预测。它假设生命是从无机起始材料通过地球化学过程在靠近深海温泉的硫化物矿物表面产生的。在过去的二十年中，针对这个主题进行了许多实验研究，并取得了一些有趣的结果。然而，其中碳/氮固定和生物分子在矿物表面组装的过程受到了过多的关注。迄今为止，参与代谢途径的中间产物的氧化还原的非生物模型被忽略了。我们研究了前生物 FeS/S/FeS(2) 氧化还原系统对几种α-羟基酸和α-酮酸（即乳酸/丙酮酸、苹果酸/草酰乙酸和乙二醇/乙醛酸）之间相互转化的氧化还原效应。我们发现，在没有 FeS 的情况下，元素硫（S）仅在高于其熔点（113°C）的温度下将α-羟基酸氧化为相应的酮酸；在 FeS 的存在下，即使在低于 S 的相变点的温度下，通过偶联反应机制，这种反应也能更有效地发生。另一方面，FeS 被证明能够可逆地还原酮酸。FeS/S/FeS(2) 氧化还原系统的这种氧化还原酶样化学表明，它可以确定生命早期进化阶段代谢中间产物的氧化还原平衡。该结果为铁-硫世界中原始氧化还原生物化学的发展提供了一种可能的途径。关键词：铁-硫世界；FeS/S/FeS(2) 氧化还原系统；氧化还原酶样化学。天体生物学 11, 471-476。
