Katz, SagieNoth, JensHorch, MariusShafaat, HannahHappe, ThomasHildebrandt, PeterZebger, Ingo2017-10-242017-10-2420162041-6520https://depositonce.tu-berlin.de/handle/11303/6891http://dx.doi.org/10.14279/depositonce-6230[FeFe] hydrogenases are biocatalytic model systems for the exploitation and investigation of catalytic hydrogen evolution. Here, we used vibrational spectroscopic techniques to characterize, in detail, redox transformations of the [FeFe] and [4Fe4S] sub-sites of the catalytic centre (H-cluster) in a monomeric [FeFe] hydrogenase. Through the application of low-temperature resonance Raman spectroscopy, we discovered a novel metastable intermediate that is characterized by an oxidized [(FeFeII)-Fe-I] centre and a reduced [4Fe4S](1+) cluster. Based on this unusual configuration, this species is assigned to the first, deprotonated H-cluster intermediate of the [FeFe] hydrogenase catalytic cycle. Providing insights into the sequence of initial reaction steps, the identification of this species represents a key finding towards the mechanistic understanding of biological hydrogen evolution.en540 Chemie und zugeordnete WissenschaftenArticle2041-653928451119