Vibrational spectroscopy reveals the initial steps of biological hydrogen evolution

Abstract

Low temperature resonance Raman spectroscopy reveals the initial, transient H-cluster intermediate during biological hydrogen production by [FeFe]-hydrogenase.

Resonance Raman spectroscopy of Fe–S proteins and their redox properties

“…RR has recently revealed structural insights into catalytic intermediate species in several of these enzymes [7, 82, 83]. Depending on the type and the source, hydrogenases can carry a variable number of different Fe–S clusters that are either essential for the ET and/or together with the binuclear center, constitute the active site.…”

“…The reduced synthetic Fe–Fe–aza-dithiolate complex (red, 514 nm excitation), thionine-oxidized apo-HydA1 (blue, 458 nm), and in vitro-matured holo-HydA1 aza-dithiolate complex (black, 488 nm excitation). Spectral regions reflecting normal modes with major contributions from Fe–S, Fe–CN, and Fe–CO coordinates are indicated.Reprinted from Katz et al [7]—published by The Royal Society of Chemistry…”

Spectroscopic investigations under whole-cell conditions provide new insight into the metal hydride chemistry of [FeFe]-hydrogenase

“…23,24 Reduction of H ox by one electron results in either H red 0 or H red (the latter also referred to as "H red H + "). 23,25,26 The H-cluster shows a reduced and possibly protonated [4Fe-4S] H cluster in H red 0 whereas in H red the [2Fe] H site is reduced and protonated. 27 Further reduction of H red generates the "super-reduced" state, H sred , identied as a [4Fe-4S] H + -[Fe(I)Fe(I)] H species.…”

Protonengekoppelte Reduktion des katalytischen [4Fe‐4S]‐Zentrums in [FeFe]‐Hydrogenasen

“…Hred und Hred′ sind zwei unterschiedliche, einfach‐reduzierte Zustände. Während der H‐Cluster in Hred das Elektron am [FeFe]‐Kofaktor trägt, liegt in Hred′ ein reduziertes [4Fe‐4S]‐Zentrum vor . Weder Hred noch Hred′ sind ESR‐aktiv .…”