title: Influence of cobalt substitution on the activity of iron-type nitrile hydratase: are cobalt type nitrile hydratases regulated by carbon monoxide?
abstract: Comamonas testosteroni Ni1 nitrile hydratase is a Fe-type nitrile hydratase whose native and recombinant forms are identical. Here, the iron of Ni1 nitrile hydratase was replaced by cobalt using a chaperone based Escherichia coli expression system. Cobalt (CoNi1) and iron (FeNi1) enzymes share identical Vmax (30 nmol min(-1) mg(-1)) and Km (200 microM) toward their substrate and identical Ki values for the known competitive inhibitors of FeNi1. However, nitrophenols used as inhibitors do display a different inhibition pattern on both enzymes. Furthermore, CoNi1 and FeNi1 are also different in their sensitivity to nitric oxide and carbon monoxide, CO being selective of the cobalt enzyme. These differences are rationalized in relation to the nature of the catalytic metal center in the enzyme.
authors.affiliation: Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, Université René Descartes, UMR 8601 CNRS, 45 Rue des Saint-Pères, 75270 Paris Cedex 06, France. marie-agnes.sari@univ-paris5.fr
authors.forename: Marie-Agnès
authors.initials: MA
authors.lastname: Sari
authors.forename: Maryse
authors.initials: M
authors.lastname: Jaouen
authors.forename: Narsing Rao
authors.initials: NR
authors.lastname: Saroja
authors.forename: Isabelle
authors.initials: I
authors.lastname: Artaud
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D002248:Carbon Monoxide / Q000494:pharmacology*; D002384:Catalysis / Q000187:drug effects; D003035:Cobalt / Q000737:chemistry*; D020604:Comamonas testosteroni / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D004926:Escherichia coli / Q000235:genetics; D006836:Hydro-Lyases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D007501:Iron / Q000737:chemistry*; D015394:Molecular Structure; D009569:Nitric Oxide / Q000494:pharmacology; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D009569:Nitric Oxide; D003035:Cobalt; D002248:Carbon Monoxide; D007501:Iron; D006836:Hydro-Lyases; C048831:nitrile hydratase