Accumulation of acyl-enzyme intermediates during turnover of penicillins by the class A beta-lactamase of Staphylococcus aureus PC1.
The interaction of dansylpenicillin with the class A Staphylococcus aureus PCI beta-lactamase yielded an accumulating intermediate with fluorescence enhanced beyond that of the substrate. Acid quenching of the reaction mixture yielded a denatured enzyme with 1 molar equivalent of dansyl group covalently bound to it. A similar quenching experiment with the PC1 beta-lactamase and [14C]benzylpenicillin yielded an enzyme with 1 molar equivalent of 14C covalently bound. These data indicate that in turnover of S-type penicillins by the PC1 beta-lactamase deacylation is rate-determining. This has not indicate previously been demonstrated for a class A beta-lactamase.
Pratt
R F
RF
Department of Chemistry, Wesleyan University, Middletown, CT 06457.
McConnell
T S
TS
Murphy
S J
SJ
D003619:Dansyl Compounds / Q000378:metabolism; D007700:Kinetics; D046911:Macromolecular Substances; D010405:Penicillinase / Q000378:metabolism*; D010406:Penicillins / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013211:Staphylococcus aureus / Q000201:enzymology*
D003619:Dansyl Compounds; D046911:Macromolecular Substances; D010406:Penicillins; D010405:Penicillinase