3S8R

Glutaryl 7-aminocephalosporanic acid (7-ACA) acylase catalyses the hydrolysis of Glutaryl 7-ACA to Glutaric acid and 7-ACA. It belongs to the family of N-terminal hydrolase (peptidase S45 family). 7-ACA is the starting compound for the synthesis of cephalosporin antibiotics and it is usually obtained industrially by chemical deacylation of cephalosporin C(CPC). Since the chemical production of 7-ACA is expensive and produce toxic chemical wastes, the enzymatic conversion of CPC to 7-ACA by 7-ACA acylase is of great interest.

In order for the enzyme to be activated towards catalysing the hydrolysis of the glutaryl form of 7-aminocephalosporanic acid, autoproteolysis must occur at the nucleophilic Ser170, revealing an N terminal nucleophile capable of inducing nucleophilic attack at the substrate's glutaryl carbonyl. The process forms two descrete proteins chains. The crystal structure depicts the non-cleaved, precursor protein, whereas the active protein froms a heterotetramer from the two resulting chains.