The oxidation-reduction and electrocatalytic properties of CO dehydrogenase from Oligotropha carboxidovorans

Publication date: Available online 14 November 2019Source: Biochimica et Biophysica Acta (BBA) - BioenergeticsAuthor(s): Palraj Kalimuthu, Mélanie Petitgenet, Dimitri Niks, Stephanie Dingwall, Jeffrey R. Harmer, Russ Hille, Paul V. BernhardtAbstractCO dehydrogenase (CODH) from the Gram-negative bacterium Oligotropha carboxidovorans is a complex metalloenzyme of the xanthine oxidase family of molybdenum-containing enzymes, bearing a unique bimolecular Mo-S-Cu active site in addition to two [2Fe-2S] clusters (FeSI and FeSII) and one equivalent of FAD. CODH catalyzes the oxidation of CO to CO2 with the concomitant introduction of reducing equivalents into the quinone pool, thus enabling the organism to utilize CO as sole source of both carbon and energy. Using a variety of EPR monitored redox titrations and spectroelectrochemistry, we report the redox potentials of CO dehydrogenase at pH 7.2 as MoVI/V, MoV/IV, FeSI, FeSII, FAD/FADH and FADH/FADH− vs NHE. These potentials are systematically higher than the corresponding potentials seen for other members of the xanthine oxidase family of Mo enzymes, and are in line with CODH utilising the higher potential quinone pool as an electron acceptor instead of pyridine nucleotides. CODH is also active when immobilised on a modified Au working electrode as demonstrated by cyclic voltammetry in the presence of CO.
Source: Biochimica et Biophysica Acta (BBA) Bioenergetics - Category: Biochemistry Source Type: research