β-Lactamase (Class A, C, and D)

β-Lactamases are enzymes produced by bacteria to inactivate β-lactam antibiotics by hydrolyzing the β-lactam ring, thus conferring resistance. The Ambler molecular classification groups them into four classes (A, B, C, D); Class A, C, and D β-lactamases are serine hydrolases that use a serine residue at the active site to hydrolyze their substrates, while class B comprises metallo-β-lactamases requiring zinc, and is not included here. Class A includes enzymes such as TEM, SHV, CTX-M, KPC; class C includes AmpC-type enzymes; and class D includes OXA-type enzymes, with each class associated with varying substrate profiles and resistance patterns. These enzymes play a major role in clinical antibiotic resistance, particularly to penicillins, cephalosporins, and carbapenems, posing a significant threat to the efficacy of current antibiotic therapies.

Other names

Beta-lactamase class ABeta-lactamase class CBeta-lactamase class DSerine beta-lactamaseClass A beta-lactamaseClass C beta-lactamaseClass D beta-lactamaseESBL enzymes (for some class A and D variants)AmpC beta-lactamase (for class C)OXA-type beta-lactamase (for class D)

Catalytic hydrolysis of the beta-lactam ring in antibiotics, rendering the drugs inactive. This involves covalent acyl-enzyme intermediate formation via serine hydrolysis at the active site. Resistance is thereby provided against broad-spectrum beta-lactams through this enzymatic inactivation.