FTIR spectroelectrochemical characterization of the Ni–Fe–Se hydrogenase from Desulfovibrio vulgaris Hildenborough

Abstract

For the first time a complete characterization by infrared spectroscopy of a Ni-Fe-Se hydrogenase in its different redox states is reported. The Ni-Fe-Se hydrogenase was isolated from Desulfovibrio vulgaris Hildenborough. Two different electron paramagnetic resonance silent and air-stable redox states that are not in equilibrium were detected. Upon reduction of these states the catalytically active states Ni-R and Ni-C appear immediately. These states are in redox equilibrium and their formal redox potential has been measured. Putative structural differences between the redox states of the active site of the Ni-Fe-Se hydrogenase are discussed.

Interaction of the active site of the Ni–Fe–Se hydrogenase from Desulfovibrio vulgaris Hildenborough with carbon monoxide and oxygen inhibitors

“…In a previous work we characterized by FTIR-spectroelectrochemistry the different redox states of the active site of the Ni-Fe-Se hydrogenase from D. vulgaris Hildenborough [14]. FTIR spectroscopy is a powerful tool for studying the hydrogenases' active sites because the CO and CN -ligands coordinated to Fe give intense bands, whose frequency values are highly sensitive to changes in the electronic structure of the active site [15,16].…”

Nickel–Iron–Selenium Hydrogenases – An Overview

“…A complete characterization by infrared spectroscopy of the [NiFeSe] Hase from D. vulgaris Hildenborough in its different redox states has been reported by De Lacey et al [58] . Two conformations of the active site were detected by FTIR for each redox state, and each conformation had a set of one CO band and two CN -bands as shown in Figure 3.…”

“…; e) reduced for 10 min at -300 mV (Ni-TR); f) reduced for 20 min at -300 mV. From [58] . Reprinted with permission from J.Biol.Inorg.Chem.. [a] data from [21] ; [b] data from [52] ;…”

“…A transient state (Ni-TR) was detected in some experiments when Ni-OX was reduced to Ni-C. The active states Ni-C and Ni-R are in redox equilibrium, and a formal redox potential of -380 mV was measured at pH 8.0 [58] . Scheme 1 shows a summary of the redox steps between the different active site states of the [NiFeSe] Hase from D. vulgaris Hildenborough, as deduced from the FTIR results.…”

“…In another application the Hys enzyme from D. vulgaris Hildenborough was bound to a gold electrode allowing for direct electron transfer, and moderate electrocatalytic currents for H 2 production were observed [31c] . [58] ). For the Vhu Hases, the sequences of VhuA and VhuU were concatenated.…”