Nickel is required for the transfer of electrons from carbon monoxide to the iron-sulfur center(s) of carbon monoxide dehydrogenase from Rhodospirillum rubrum

Journal Article · Tue Jun 13 00:00:00 EDT 1989 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00438a010· OSTI ID:5301725

Ensign, S A; Bonam, D; Ludden, P W ^[1]

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1. Univ. of Wisconsin, Madison (USA)

The role of nickel in CO oxidation and electron flow was investigated in carbon monoxide dihydrogenase from Rhodospirillum rubrum. The Fe-S center of oxidized, nickel-containing (holo) CO dehydrogenase were completely reduced within 1 min of exposure to CO. The Fe-S centers of oxidized, nickel-deficient (apo) CO dehydrogenase were not reduced during a 35-min incubation in the presence of CO. Apo-CO dehydrogenase Fe-S centers were reduced by dithionite. The Fe-S centers of cyanide-inhibited, holo-CO dehydrogenase were not reduced in the presence of CO but were reduced by dithionite. Treatment of apo-CO dehydrogenase with cobalt(II), zinc(II), and iron(II) resulted in association of these metal ions (0.70, 1.2, and 0.86 mol of M{sup 2+}/mol, respectively) with the protein but no increase in specific activity. Purified holo-CO dehydrogenase contained 1.1 mol of nickel/mol of protein and could not be further activated upon addition of NiCl{sub 2}, suggesting the presence of one catalytic nickel site on the enzyme. The M{sup 2+}-treated enzymes could not be further activated by addition of NiCl{sub 2} as opposed to the untreated apoenzyme, whose activity was stimulated 50-100-fold to the level of holoenzyme upon addition of NiCl{sub 2}. When placed under CO, the Fe-S centers of the cobalt-treated enzyme became reduced over a 35-min time course, as opposed to the zinc- and iron-treated enzymes, which remained oxidized. The authors conclude that nickel, or an appropriate nickel analogue in the nickel site, mediates electron flow from CO to the Fe-S centers of CO dehydrogenase.

• DOE Contract Number: FG02-87ER13691
• OSTI ID: 5301725
• Journal Information: Biochemistry; (USA), Vol. 28:12; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CARBON MONOXIDE
OXIDATION
NICKEL CHLORIDES
BIOLOGICAL EFFECTS
OXIDOREDUCTASES
ELECTRON TRANSFER
IRON COMPOUNDS
SULFUR COMPOUNDS
ULTRAVIOLET SPECTRA
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
ENZYMES
HALIDES
HALOGEN COMPOUNDS
NICKEL COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
SPECTRA
TRANSITION ELEMENT COMPOUNDS
550200* - Biochemistry