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Publication Abstract from PubMed

Metal-dependent formate dehydrogenases are important enzymes due to their activity of CO2 reduction to formate. The tungsten-containing FdhAB formate dehydrogenase from Desulfovibrio vulgaris Hildenborough is a good example displaying high activity, simple composition, and a notable structural and catalytic robustness. Here, we report the first spectroscopic redox characterization of FdhAB metal centers by EPR. Titration with dithionite or formate leads to reduction of three [4Fe-4S](1+) clusters, and full reduction requires Ti(III)-citrate. The redox potentials of the four [4Fe-4S](1+) centers range between -250 and -530 mV. Two distinct W(V) signals were detected, WD(V) and WF(V), which differ in only the g2-value. This difference can be explained by small variations in the twist angle of the two pyranopterins, as determined through DFT calculations of model compounds. The redox potential of W(VI/V) was determined to be -370 mV when reduced by dithionite and -340 mV when reduced by formate. The crystal structure of dithionite-reduced FdhAB was determined at high resolution (1.5 A), revealing the same structural alterations as reported for the formate-reduced structure. These results corroborate a stable six-ligand W coordination in the catalytic intermediate W(V) state of FdhAB.

Spectroscopic and Structural Characterization of Reduced Desulfovibrio vulgaris Hildenborough W-FdhAB Reveals Stable Metal Coordination during Catalysis.,Oliveira AR, Mota C, Klymanska K, Biaso F, Romao MJ, Guigliarelli B, Pereira IC ACS Chem Biol. 2022 Jul 15;17(7):1901-1909. doi: 10.1021/acschembio.2c00336. Epub, 2022 Jun 29. PMID:35766974^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.