lactamase Biochem.
(ˈlæktəmeɪz, -s)
[f. lactam + -ase.]
β-lactamase: any of the enzymes (produced by certain bacteria) which cause the breaking of the carbon-nitrogen bond in the lactam ring of penicillins and cephalosporins (so rendering them ineffective as antibiotics).
| 1964 Jrnl. Gen. Microbiol. XXXVI. 206 Amidase-forming coliform organisms did not attack the 6-APA nucleus, whereas β-lactamase-forming coliform organisms opened the lactam ring. 1971 N. Citri in P. D. Boyer et al. Enzymes (ed. 3) IV. ii. 24 The role of penicillinase and other β-lactamases in conferring resistance to penicillins and the closely related cephalosporins has been amply demonstrated. |