4hst

Publication Abstract from PubMed

The crystal structure of wild-type form of glutaryl-7-ACA acylase from Pseudomonas N176 and a double mutant of the protein (His57betaSer/His70betaSer) that displays enhanced catalytic efficiency on cephalosporin C over glutaryl-7-aminocephalosporanic acid has been determined. The structures show a heterodimer made up of an alpha chain (229 residues) and a beta chain (543 residues) with a deep cavity, which constitutes the active site. Comparison of the wild-type and mutant structures provide insights into the molecular reasons for the observed enhanced specificity on cephalosporin C over glutaryl-7-aminocephalosporanic acid and offered the basis to evolve a further improve enzyme variant. The nucleophilic catalytic serine residue, Ser1beta, is situated at the base of the active site cavity. The electron density reveals a ligand covalently bound to the catalytic serine residue such that a tetrahedral adduct is formed. This is proposed to mimic the transition state of the enzyme for both the maturation step and the catalysis of the substrates. A view of the transitions state configuration of the enzyme provides important insights into the mechanism of substrate binding and catalysis.

Structure of a class III engineered cephalosporin acylase. Comparisons to class I acylase and implications for differences in substrate specificity and catalytic activity.,Golden E, Paterson R, Tie WJ, Anandan A, Flematti G, Molla G, Rosini E, Pollegioni L, Vrielink A Biochem J. 2013 Feb 4. PMID:23373797^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.