Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI 48109.
Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125.
Proc Natl Acad Sci U S A. 2024 Sep 17;121(38):e2318692121. doi: 10.1073/pnas.2318692121. Epub 2024 Sep 9.
Modern life requires many different metal ions, which enable diverse biochemical functions. It is commonly assumed that metal ions' environmental availabilities controlled the evolution of early life. We argue that evolution can only explore the chemistry that life encounters, and fortuitous chemical interactions between metal ions and biological compounds can only be selected for if they first occur sufficiently frequently. We calculated maximal transition metal ion concentrations in the ancient ocean, determining that the amounts of biologically important transition metal ions were orders of magnitude lower than ferrous iron. Under such conditions, primitive bioligands would predominantly interact with Fe(II). While interactions with other metals in certain environments may have provided evolutionary opportunities, the biochemical capacities of Fe(II), Fe-S clusters, or the plentiful magnesium and calcium could have satisfied all functions needed by early life. Primitive organisms could have used Fe(II) exclusively for their transition metal ion requirements.
现代生活需要多种不同的金属离子，这些金属离子使多样化的生化功能成为可能。人们普遍认为，金属离子在环境中的可用性控制了早期生命的进化。我们认为，进化只能探索生命所遇到的化学物质，只有当金属离子和生物化合物之间的偶然化学相互作用足够频繁地发生时，它们才能被选择。我们计算了古代海洋中过渡金属离子的最大浓度，结果表明，对生物重要的过渡金属离子的数量要低几个数量级。在这种情况下，原始的生物配体将主要与 Fe(II)相互作用。虽然在某些环境中与其他金属的相互作用可能提供了进化的机会，但 Fe(II)、Fe-S 簇或丰富的镁和钙的生物化学能力可能已经满足了早期生命所需的所有功能。原始生物可能只将 Fe(II)专门用于其过渡金属离子需求。
