|-
| align="center" colspan="2" |
|-
| colspan="2" bgcolor="#dddddd" | Identifiers
|-
| bgcolor="#e7dcc3" | Symbol(s)
| bgcolor="#eeeeee" | [LACTB]
|-
| bgcolor="#e7dcc3" | Entrez
| bgcolor="#eeeeee" | [114294]
|- class="hiddenStructure"
| bgcolor="#e7dcc3" | OMIM
| bgcolor="#eeeeee" | [608440]
|-
| bgcolor="#e7dcc3" | RefSeq
| bgcolor="#eeeeee" | [NM_171846]
|-
| bgcolor="#e7dcc3" | UniProt
| bgcolor="#eeeeee" | [P83111]
|- class="hiddenStructure"
| bgcolor="#e7dcc3" | PDB
| bgcolor="#eeeeee" | []
|-
| colspan="2" bgcolor="#dddddd" | Other data
|- class="hiddenStructure"
| bgcolor="#e7dcc3" | EC number
| bgcolor="#eeeeee" | [3.5.2.6]
|-
| bgcolor="#e7dcc3" | Locus
| bgcolor="#eeeeee" | Chr. 15[q22.1]
|-
|}
Beta-lactamase is a type of enzyme (EC [3.5.2.6]) 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.
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
