Premium
Evaluation of inhibition of the carbenicillin‐hydrolyzing β‐lactamase PSE‐4 by the clinically used mechanism‐based inhibitors
Author(s) -
Therrien Christian,
Kotra Lakshmi P.,
Sanschagrin François,
Mobashery Shahriar,
Levesque Roger C.
Publication year - 2000
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(00)01342-9
Subject(s) - carbenicillin , sulbactam , chemistry , enzyme , clavulanic acid , tazobactam , acylation , enzyme kinetics , biochemistry , stereochemistry , active site , antibiotics , catalysis , amoxicillin , ampicillin , antibiotic resistance , imipenem
Characterization of the biochemical steps in the inactivation chemistry of clavulanic acid, sulbactam and tazobactam with the carbenicillin‐hydrolyzing β‐lactamase PSE‐4 from Pseudomonas aeruginosa is described. Although tazobactam showed the highest affinity to the enzyme, all three inactivators were excellent inhibitors for this enzyme. Transient inhibition was observed for the three inactivators before the onset of irreversible inactivation of the enzyme. Partition ratios ( k cat / k inact ) of 11, 41 and 131 were obtained with clavulanic acid, tazobactam and sulbactam, respectively. Furthermore, these values were found to be 14‐fold, 3‐fold and 80‐fold lower, respectively, than the values obtained for the clinically important TEM‐1 β‐lactamase. The kinetic findings were put in perspective by determining the computational models for the pre‐acylation complexes and the immediate acyl‐enzyme intermediates for all three inactivators. A discussion of the pertinent structural factors is presented, with PSE‐4 showing subtle differences in interactions with the three inhibitors compared to the TEM‐1 enzyme.