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Beta-lactamase is a type of enzyme () produced by some bacteria that is responsible for their resistance to beta-lactam antibiotics like penicillins, cephalosporins, cephamycins and carbapenems. These antibiotics have a common element in their molecular structure: a four-atom ring known as a beta-lactam. The lactamase enzyme breaks that ring open, deactivating the molecule's antibacterial properties.
The structure of a Streptomyces β lactamase is given by .
Penicillinase
Penicillinase is a particular type of β lactamase, showing specificity for penicillins, again by hydrolysing the beta-lactam ring. Molecular weights of the various penicillinases tend to cluster near 50,000.
Penicillinase was the first β lactamase to emerge, due to the early dependence on penicillin. Penicillinase-resistant β lactams were then developed such as methicillin, although there is widespread resistance to these now also (see MRSA).
Reference
- Jacoby GA, Munoz-Price LS. The new β-lactamases. N Engl J Med 2005;352:380-91. PMID 15673804
See also
"Beta-lactamase"