Open AccessKinetics of Interaction between the Exocellular DD‐Carboxypeptidase‐Transpeptidase from Streptomyces R61 and β‐Lactam Antibiotics
Author(s) -
FRÈRE JeanMarie,
GHUYSEN JeanMarie,
IWATSUBO Motohiro
Publication year - 1975
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1975.tb02307.x
Subject(s) - antibiotics , benzylpenicillin , chemistry , enzyme , carboxypeptidase , stereochemistry , lactam , streptomyces , kinetics , dissociation (chemistry) , biochemistry , bacteria , biology , penicillin , organic chemistry , physics , quantum mechanics , genetics
The simplest model for the interaction between the exocellular DD‐carboxypeptidase‐trans‐peptidase from Streptomyces R61 and β‐lactam antibiotics involves the three following steps. (a) the formation of a reversible equimolar enzyme · antibiotic complex; (b) the irreversible transformation of this complex into a modified enzyme · antibiotic complex; and (c) the breakdown of this latter complex and the concomitant release of a regenerated enzyme and a modified antibiotic molecule. The dissociation constant for step 1 and the rate constants for steps 2 and 3 were measured with various β‐lactam antibiotics. With an antibiotic such as benzylpenicillin, which behaves as a good ‘substrate’, steps 1 and 2 occur at enzymic velocities, whereas step 3 occurs at a very low velocity and hence is responsible for the low efficiency of the overall process.