Oxygen effects on the nickel- and iron-containing hydrogenase from Azotobacter vinelandii

Journal Article · Tue Feb 21 04:00:00 EST 1989 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00430a025· OSTI ID:5516791

Seefeldt, L C; Arp, D J ^[1]

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1. Univ. of California, Riverside (USA)

The effects of O{sub 2} on membrane-bound Azotobacter vinelandii hydrogenase in both the membrane-associated and purified states were characterized. O{sub 2} was a rapid-equilibrium, reversible inhibitor both of H{sub 2} oxidation/electron acceptor reduction activity and of the exchange activity. O{sub 2} inhibition was noncompetitive versus the electron acceptor methylene blue and uncompetitive versus the substrate H{sub 2}. O{sub 2} inhibition was rapidly reversed by removal of the O{sub 2}. In addition to an O{sub 2}-independent, reversible inhibition of hydrogenase, a time-dependent, irreversible inactivation by O{sub 2} of both H{sub 2} oxidation and exchange activities for this hydrogenase was demonstrated. The irreversible inactivation followed a first-order process. The inactivation by O{sub 2} was protected against by the substrate H{sub 2} in a concentration-dependent manner. This is the first report of H{sub 2} protection from O{sub 2}-dependent, irreversible inactivation for any hydrogenase. The competitive inhibitor CO did not affect the irreversible inactivation by O{sub 2} or the protection by H{sub 2}. A model is proposed that outlines various oxidation states of this hydrogenase and the effects of O{sub 2} on each state.

• DOE Contract Number: FG03-84ER13257
• OSTI ID: 5516791
• Journal Information: Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 28:4; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AZOTOBACTER
BACTERIA
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL EFFECTS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CELL CONSTITUENTS
CELL MEMBRANES
CHALCOGENIDES
ELEMENTS
ENZYME INHIBITORS
ENZYMES
HYDROGEN COMPOUNDS
HYDROGENASES
INACTIVATION
IRON COMPOUNDS
KINETICS
MEMBRANES
MICROORGANISMS
NICKEL COMPOUNDS
NONMETALS
OXIDES
OXIDOREDUCTASES
OXYGEN
OXYGEN COMPOUNDS
REACTION KINETICS
TRANSITION ELEMENT COMPOUNDS
TRITIUM COMPOUNDS