Serine beta-Lactamase (Class A)

Serine beta-lactamases (class A) are enzymes produced by bacteria that confer resistance to beta-lactam antibiotics, such as penicillins and cephalosporins, by hydrolyzing the characteristic beta-lactam ring of these drugs. This enzymatic activity renders the antibiotics ineffective, allowing bacteria to survive in their presence. The catalytic process involves two main steps: acylation and deacylation. Notable examples include TEM-1, SHV, CTX-M, and KPC-type enzymes. These enzymes are major contributors to bacterial resistance against widely used antibiotics. They are found predominantly in Gram-negative bacteria but also occur in some Gram-positive species like staphylococci. Class A serine β-lactamases can often be inhibited by compounds such as clavulanic acid or tazobactam; however, some variants show reduced susceptibility or resistance even to these inhibitors.

Other names

Class A beta-lactamaseClass A serine beta-lactamase

Acylation–deacylation via nucleophilic attack on β-lactam ring