title: The catalytic mechanism of amidase also involves nitrile hydrolysis.
abstract: The amidase from Rhodococcus rhodochrous J1, which hydrolyzes an amide to an acid and ammonium, was surprisingly found to catalyze the hydrolytic cleavage of the C-N triple bond in a nitrile to form an acid and ammonium stoichiometrically. The amidase exhibited a Km of 3.26 mM for benzonitrile in contrast to that of 0.15 mM for benzamide as the original substrate, but the Vmax for benzonitrile was about 116000 of that for benzamide. A mutant amidase containing alanine instead of Ser195, which is essential for amidase catalytic activity, showed no nitrilase activity, demonstrating that this residue plays a crucial role in the hydrolysis of nitriles as well as amides.
authors.affiliation: Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kobayashi
authors.forename: M
authors.initials: M
authors.lastname: Goda
authors.forename: S
authors.initials: S
authors.lastname: Shimizu
mesh_terms: D000581:Amidohydrolases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D000641:Ammonia / Q000378:metabolism; D019817:Benzoic Acid / Q000378:metabolism; D002384:Catalysis; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli; D006868:Hydrolysis; D009570:Nitriles / Q000378:metabolism* / Q000494:pharmacology; D012240:Rhodococcus / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D004791:Enzyme Inhibitors; D009570:Nitriles; D000641:Ammonia; D019817:Benzoic Acid; C014356:benzonitrile; D000581:Amidohydrolases; C019665:amidase