title: Catalysis by hog-kidney aminoacylase does not involve a covalent intermediate.
abstract: Hog kidney aminoacylase (N-acylamino acid amidohydrolase; acylase I) is shown to catalyze the exchange of acetate oxygens with water at a significant rate only when alanine is present simultaneously. These studies, conducted using the 18O-isotope induced shift on 13C-NMR spectra, provide evidence in favor of a linear kinetic mechanism as opposed to a 'ping-pong' double-displacement mechanism. At pH values above neutrality, aminoacylase I also catalyzes the exchange of alanine oxygens with those of water. Ionic strength and pH effects on the kinetics of aminoacylase I are examined and the results are interpreted in terms of a model of the enzyme active site.
mesh_terms: D000085:Acetates / Q000378:metabolism; D000409:Alanine / Q000502:physiology; D000581:Amidohydrolases / Q000378:metabolism*; D000818:Animals; D002384:Catalysis; D006863:Hydrogen-Ion Concentration; D007668:Kidney / Q000201:enzymology*; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D013552:Swine; D014867:Water / Q000378:metabolism
chemical_list: D000085:Acetates; D014867:Water; D000581:Amidohydrolases; C019672:aminoacylase I; D000409:Alanine