Unusual structures and unknown roles of FeS clusters in metalloenzymes seen from a resonance Raman spectroscopic perspective

The universe of known biological FeS clusters is constantly enlarging. Besides the conventional, well described [2Fe–2S], [3Fe–4S] and cubane [4Fe–4S] clusters, novel, unprecedented structures are emerging. They include unusually coordinated with additional sulfur atoms, e.g., [4Fe–5S], [5Fe–5S], [4Fe–4S]-5S-[4Fe–4S], [8Fe–7S], [8Fe–9S] [8Fe–8S–C] heteronuclear [Ni–4Fe–4S], [2Ni–4Fe–4S], [4Fe–4S]-[2Ru], [Me–7Fe–9S–C–(homocitrate)] that undertake versatile physiological roles in activation small molecules (H2, CO2, CO N2) sulfuration different compounds (e.g., t-RNAs, biotin lipoic acid) biology. A few characterized by highly distorted geometries, non-cubane center hydrogenase-related [4Fe–3S] cluster, contain atypical ligations or vacant coordination sites, which confer them novel functions far from common electron transfer. Herein, we single out found i) hydrogenases ensure sustainable hydrogen cycling, promising a clean fuel production future, ii) radical-SAM enzymes can inspire applied catalysis due to an intrinsic flexibility radical chemistry, iii) standard cluster still unknown function DNA repair enzymes, offer possibility interfere pathogens improve it humans. Focusing on abovementioned demonstrate unique power resonance Raman spectroscopy unveil remarkable features centers, has contributed our understanding unusual disentangling functions.