In previous studies, several amino acids of the active site of class A beta-lactamases have been modified by site-directed mutagenesis. On the basis of the catalytic mechanism proposed for the Streptomyces albus G beta-lactamase [Lamotte-Brasseur, Dive, Dideberg, Charlier, Frère & Ghuysen (1991) Biochem. J. 279, 213-221], the influence that these mutations exert on the hydrogen-bonding network of the active site has been analysed by molecular mechanics. The results satisfactorily explain the effects of the mutations on the kinetic parameters of the enzyme's activity towards a set of substrates. The present study also shows that, upon binding a properly structured beta-lactam compound, the impaired cavity of a mutant enzyme can readopt a functional hydrogen-bonding-network configuration.
Streptomyces albus G serine β-lactamase. Probing of the catalytic mechanism via molecular modelling of mutant enzymes
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J Lamotte-Brasseur, F Jacob-Dubuisson, G Dive, J M Frère, J M Ghuysen; Streptomyces albus G serine β-lactamase. Probing of the catalytic mechanism via molecular modelling of mutant enzymes. Biochem J 15 February 1992; 282 (1): 189–195. doi: https://doi.org/10.1042/bj2820189
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