Class D beta lactamases are able to break down oxacillin and cloxacillin thus playing a vital role in antibiotic resistance in bacteria as they can prevent these compounds from inhibiting the DD peptidases involved in bacterial cell wall synthesis. As part of the family of serine beta lactamases, which also includes classes A B and C of the beta lactamases, they share significant homology with the DD peptidases, indicating that they diverged from a common ancestor. However, they are able to hydrolyse the acyl enzyme intermediate that forms through initial nucleophilic attack on the beta-lactam ring much more quickly, thus do not become inhibited by the beta lactams in the same way.
Defined by 6 residues: SER:A-46 [auth A-67]LYS:A-49 [auth A-70]SER:A-93 [auth A-115]SER:A-98 [auth A-120]TRP:A-138 [auth A-160]ALA:A-193 [auth A-215]