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

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

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

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

---

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), Vol. 29:8; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

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