Carbonyl sulfide inhibition of CO dehydrogenase from Rhodospirillum rubrum

Journal Article · Tue Aug 22 00:00:00 EDT 1989 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00443a007· OSTI ID:5301713

Hyman, M R; Ensign, S A; Arp, D J; Ludden, P W ^[1]

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1. Univ. of California, Riverside (USA)

Carbonyl sulfide (COS) has been investigated as a rapid-equilibrium inhibitor of CO oxidation by the CO dehydrogenase purified from Rhodospirillum rubrum. The kinetic evidence suggests that the inhibition by COS is largely competitive versus CO (K{sub i} = 2.3 {mu}M) and uncompetitive versus methylviologen as electron acceptor. The data are compatible with a ping-pong mechanism for CO oxidation and COS inhibition. Unlike the substrate CO, COS does not reduce the iron-sulfur centers of dye-oxidized CO dehydrogenase and thus is not an alternative substrate for the enzyme. However, like CO, COS is capable of protecting CO dehydrogenase from slow-binding inhibition by cyanide. A true binding constant (K{sub D}) of 2.2 {mu}M for COS has been derived on the basis of the saturable nature of COS protection against cyanide inhibition. The ability of CO, CO{sub 2}, COS, and related CO/CO{sub 2} analogues to reverse cyanide inhibition of CO dehydrogenase is also demonstrated. The kinetic results are interpreted in terms of two binding sites for CO on CO dehydrogenase from R. rubrum.

• OSTI ID: 5301713
• Journal Information: Biochemistry; (USA), Vol. 28:17; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CARBON SULFIDES
BIOLOGICAL EFFECTS
OXIDOREDUCTASES
BIOCHEMICAL REACTION KINETICS
RHODOSPIRILLUM
ENZYME ACTIVITY
CARBON MONOXIDE
CYANIDES
OXIDATION
PURIFICATION
RECEPTORS
BACTERIA
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
ENZYMES
KINETICS
MEMBRANE PROTEINS
MICROORGANISMS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PROTEINS
REACTION KINETICS
SULFIDES
SULFUR COMPOUNDS
550200* - Biochemistry