Prebiotic chemistry was likely mediated by metals, but how such prebiotic chemistry progressed into the metabolic-like networks needed to sustain life remains unclear. Here we experimentally delineate a potential path from prebiotically plausible iron–sulfur peptide catalysts to the types of pH gradients exploited by all known living organisms. Iron–sulfur peptides cooperatively accept electrons from NADH in a manner that is only partially mediated by ionic interactions. The electrons are then either passed to a terminal electron acceptor, such as hydrogen peroxide, or to an intermediate carrier, such as ubiquinone. The reduction of hydrogen peroxide leads to the production of hydroxide, which then contributes to the formation of a pH gradient across late protocell membranes. The data are consistent with the activity of prebiotic iron–sulfur peptide catalysts providing a selective advantage by equipping protocells with a pathway that connects catabolism to anabolism.

益生元化学可能是由金属介导的，但尚不清楚这种益生元化学如何发展成维持生命所需的类似代谢的网络。在这里，我们实验性地描绘了从益生元似的铁-硫肽催化剂到所有已知活生物体利用的pH梯度类型的潜在途径。铁硫肽以仅部分通过离子相互作用介导的方式协同接受来自NADH的电子。然后，电子要么传递到末端电子受体（例如过氧化氢），要么传递到中间载体（例如泛醌）。过氧化氢的还原导致氢氧化物的产生，然后产生氢氧化物，从而在整个原始细胞膜上形成pH梯度。