Activation of the nickel-deficient carbon monoxide dehydrogenase from Rhodospirillum rubrum: Kinetic characterization and reductant requirement

Journal Article · Tue Feb 27 04:00:00 EST 1990 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00460a029· OSTI ID:7190184

Ensign, S A; Campbell, M J; Ludden, P W ^[1]

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1. Univ. of Wisconsin, Madison (USA)

The requirements for and kinetics of the activation of the nickel-deficient (apo) CO dehydrogenase from Rhodospirillum rubrum by exogenous nickel have been investigated. The activation is strictly dependent upon the presence of a low-potential one-electron reductant. Sodium dithionite and reduced methylviologen are suitable reductants, whereas reduced indigo carmine and the two-electron reductants sodium borohydride, NADH, and dithiothreitol are ineffective in stimulating activation. The midpoint potential for activation was observed at approximately {minus}475 mV. The ability of a reductant to stimulate activation is correlated with the reduced state of the enzyme Fe{sub 4}-S{sub 4} centers. The activation follows apparent first-order kinetics in a saturable fashion, yielding a rate constant of 0.157 min{sup {minus}1} at saturating concentration of nickel. The initial rate at which the enzyme is activated by NiCl{sub 2} is also a saturable process, yielding a dissociation constant (K{sub D}) of 755 {mu}M for the initial association of nickel and enzyme. Cadmium(II), zinc(II), cobalt(II), and iron(II) are competitive inhibitors of nickel activation with inhibition constants of 2.44, 4.16, 175, and 349 {mu}M, respectively. Manganese(II), calcium(II), and magnesium(II) exhibit no inhibition of activation.

• DOE Contract Number: FG02-87ER13691
• OSTI ID: 7190184
• Journal Information: Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 29:8; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

560300* -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALKALINE EARTH METAL COMPOUNDS
BACTERIA
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL EFFECTS
CADMIUM COMPOUNDS
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATIONS
CHALCOGENIDES
CHARGED PARTICLES
CHLORIDES
CHLORINE COMPOUNDS
COBALT COMPOUNDS
ENZYME INDUCTION
ENZYMES
GENE REGULATION
HAEM DEHYDROGENASES
HALIDES
HALOGEN COMPOUNDS
IONS
IRON COMPOUNDS
KINETICS
MAGNESIUM COMPOUNDS
MICROORGANISMS
NICKEL CHLORIDES
NICKEL COMPOUNDS
OXIDES
OXIDOREDUCTASES
OXYGEN COMPOUNDS
REACTION KINETICS
RHODOSPIRILLUM
TRANSITION ELEMENT COMPOUNDS
ZINC COMPOUNDS