Role of geochemical protoenzymes (geozymes) in primordial metabolism: specific abiotic hydride transfer by metals to the biological redox cofactor NAD.

Hydrogen gas, H , is generated in serpentinizing hydrothermal systems, where it has supplied electrons and energy for microbial communities since there was liquid water on Earth. In modern metabolism, H is converted by hydrogenases into organically bound hydrides (H ), for example, the cofactor NADH. It transfers hydrides among molecules, serving as an activated and biologically harnessed form of H .

The Autotrophic Core: An Ancient Network of 404 Reactions Converts H, CO, and NH into Amino Acids, Bases, and Cofactors.

The metabolism of cells contains evidence reflecting the process by which they arose. Here, we have identified the ancient core of autotrophic metabolism encompassing 404 reactions that comprise the reaction network from H, CO, and ammonia (NH) to amino acids, nucleic acid monomers, and the 19 cofactors required for their synthesis. Water is the most common reactant in the autotrophic core, indicating that the core arose in an aqueous environment.

The ambivalent role of water at the origins of life.

Life as we know it would not exist without water. However, water molecules not only serve as a solvent and reactant but can also promote hydrolysis, which counteracts the formation of essential organic molecules. This conundrum constitutes one of the central issues in origin of life.

Catalysts, autocatalysis and the origin of metabolism.

If life on Earth started out in geochemical environments like hydrothermal vents, then it started out from gasses like CO, N and H. Anaerobic autotrophs still live from these gasses today, and they still inhabit the Earth's crust. In the search for connections between abiotic processes in ancient geological systems and biotic processes in biological systems, it becomes evident that chemical activation (catalysis) of these gasses and a constant source of energy are key.