Modeling and Experimental Analysis of Cephalosporin C Acylase and Its Mutant

Abstract

7-amino cephalosporanic acid (7-ACA) is the crucial intermediate for the synthesis of semi-synthetic antibiotics, which is currently prepared by two-step biocatalysis using D-amino acid oxidase and glutaryl-7-amino cephalosporanic acid acylase (GL-7-ACA acylase) starting from cephalosporin C (CPC). Compared with the two-step enzymatic method, one-step method is more efficient and economical. But, the available Cephalosporin C acylase (CPC acylase) always take glutaryl-7-amino cephalosporanic acid (GL-7-ACA) as their primary substrate, and have low catalytic activities towards CPC to be used in industry. We investigated the catalytic mechanism of CPC acylase by the sequence alignment, homology modeling, and active site analysis to a series of CPC acylases from Pseudomonas where some effective mutations have been reported for activity enhancement. Two CPC acylases coded by the genes acyII and S12 are studied intensively for the interaction between the amino acid residues in the activity region and the substrate CPC based upon the complex structure obtained from the homology modeling and molecular docking. Furthermore, the catalytic parameters of the two CPC acylases were measured experimentally in order to corroborate the modeling analysis and propose potential designing strategy for improvement of enzymic activity.