Cyanide inactivation of hydrogenase from Azotobacter vinelandii

Journal Article · Thu Jun 01 04:00:00 EDT 1989 · Journal of Bacteriology; (USA)

OSTI ID:6936059

Seefeldt, L C; Arp, D J ^[1]

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1. Univ. of California, Riverside (USA)

The effects of cyanide on membrane-associated and purified hydrogenase from Azotobacter vinelandii were characterized. Inactivation of hydrogenase by cyanide was dependent on the activity (oxidation) state of the enzyme. Active (reduced) hydrogenase showed no inactivation when treated with cyanide over several hours. Treatment of reversibly inactive (oxidized) states of both membrane-associated and purified hydrogenase, however, resulted in a time-dependent, irreversible loss of hydrogenase activity. The rate of cyanide inactivation was dependent on the cyanide concentration and was an apparent first-order process for purified enzyme (bimolecular rate constant, 23.1 M{sup {minus}1} min{sup {minus}1} for CN{sup {minus}}). The rate of inactivation decreased with decreasing pH. ({sup 14}C)cyanide remained associated with cyanide-inactivated hydrogenase after gel filtration chromatography, with a stoichiometry of 1.7 mol of cyanide bound per mol of inactive enzyme. The presence of saturating concentrations of CO had no effect on the rate or extent of cyanide inactivation of hydrogenases. The results indicate that cyanide can cause a time-dependent, irreversible inactivation of hydrogenase in the oxidized, activatable state but has no effect when hydrogenase is in the reduced, active state.

• DOE Contract Number: FG03-84ER13257
• OSTI ID: 6936059
• Journal Information: Journal of Bacteriology; (USA), Journal Name: Journal of Bacteriology; (USA) Vol. 171:6; ISSN JOBAA; ISSN 0021-9193
• Country of Publication: United States
• Language: English

Related Subjects

550201 -- Biochemistry-- Tracer Techniques
560300* -- Chemicals Metabolism & Toxicology
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AZOTOBACTER
BACTERIA
CARBON 14 COMPOUNDS
CYANIDES
ENZYME ACTIVITY
ENZYMES
HYDROGENASES
INACTIVATION
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MICROORGANISMS
OXIDOREDUCTASES
SENSITIVITY
TOXICITY
TRACER TECHNIQUES