Characterization of the Oxygen Tolerance of a Hydrogenase Linked to a Carbon Monoxide Oxidation Pathway in Rubrivivax gelatinosus

• DOI: 10.1128/aem.68.6.2633-2636.2002
• Publication Date: 2002-07-27T10:09:29Z
• Authors: Pin-Ching Maness; Sharon Smolinski; Anne C. Dillon; Michael J. Heben; Paul F. Weaver
• Keywords: 0301 basic medicine; Carbon Monoxide; Photolysis; Water; 7. Clean energy; 6. Clean water; Oxygen; 03 medical and health sciences; Hydrogenase; 13. Climate action; Proteobacteria; Oxidation-Reduction; Hydrogen

ABSTRACT

A hydrogenase linked to the carbon monoxide oxidation pathway in Rubrivivax gelatinosus displays tolerance to O 2 . When either whole-cell or membrane-free partially purified hydrogenase was stirred in full air (21% O 2 , 79% N 2 ), its H 2 evolution activity exhibited a half-life of 20 or 6 h, respectively, as determined by an anaerobic assay using reduced methyl viologen. When the partially purified hydrogenase was stirred in an atmosphere containing either 3.3 or 13% O 2 for 15 min and evaluated by a hydrogen-deuterium (H-D) exchange assay, nearly 80 or 60% of its isotopic exchange rate was retained, respectively. When this enzyme suspension was subsequently returned to an anaerobic atmosphere, more than 90% of the H-D exchange activity was recovered, reflecting the reversibility of this hydrogenase toward O 2 inactivation. Like most hydrogenases, the CO-linked hydrogenase was extremely sensitive to CO, with 50% inhibition occurring at 3.9 μM dissolved CO. Hydrogen production from the CO-linked hydrogenase was detected when ferredoxins of a prokaryotic source were the immediate electron mediator, provided they were photoreduced by spinach thylakoid membranes containing active water-splitting activity. Based on its appreciable tolerance to O 2 , potential applications of this hydrogenase are discussed.