title: Deacylation activity of cephalosporin acylase to cephalosporin C is improved by changing the side-chain conformations of active-site residues.
abstract: Semisynthetic cephalosporins are primarily synthesized from 7-aminocephalosporanic acid (7-ACA), mainly by environmentally toxic chemical deacylation of cephalosporin C (CPC). Thus, the enzymatic conversion of CPC to 7-ACA by cephalosporin acylase (CA) would be very interesting. However, CAs use glutaryl-7-ACA (GL-7-ACA) as a primary substrate and the enzymes have low turnover rates for CPC. The active-site residues of a CA were mutagenized to various residues to increase the deacylation activity of CPC, based on the active-site conformation of the CA structure. The aim was to generate sterically favored conformation of the active-site to accommodate the D-alpha-aminoadipyl moiety of CPC, the side-chain moiety that corresponds to the glutaryl moiety of GL-7-ACA. A triple mutant of the CA, Q50betaM/Y149alphaK/F177betaG, showed the greatest improvement of deacylation activity to CPC up to 790% of the wild-type. Our current study is an efficient method for improving the deacylation activity to CPC by employing the structure-based repetitive saturation mutagenesis.
mesh_terms: D000215:Acylation; D001665:Binding Sites; D002511:Cephalosporins / Q000378:metabolism*; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D010399:Penicillin Amidase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D002511:Cephalosporins; C025163:cephalosporin C; D010399:Penicillin Amidase