Open AccessInhibition of the Aliphatic Amidase from Pseudomonas aeruginosa by Urea and Related Compounds
Author(s) -
GREGORIOU Mary,
BROWN Paul R.
Publication year - 1979
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1979.tb13018.x
Subject(s) - amidase , urea , acetamide , chemistry , biochemistry , enzyme , urease , enzyme kinetics , active site , kinetics , organic chemistry , physics , quantum mechanics
The time‐dependent inhibition of amidase from Pseudomonas aeruginosa strain AI 3 by urea, hydroxyurea and cyanate displayed saturation kinetics fitting a model for the reaction sequence in which formation of a complex in a reversible step was followed by an irreversible step. Altered amidases from mutant strains AIU 1N and OUCH 4, selected for their resistance to inhibition of growth by urea and hydroxyurea respectively, had altered kinetic constants for inhibition indicating reduced binding capacity for the inhibitors. The substrate acetamide protected AI 3 amidase against inhibition by urea, and altered K i values for inhibition of the mutant amidases were paralleled by alterations in K m values for acetamide indicating that urea acted at the active site. Inhibition of AI 3 amidase involved the binding of one molecule of urea per molecule of enzyme. Urea inhibited amidase slowly regained activity at pH 7.2 through release of urea.