Enhancing Penicillin G
Acylase Stability by Site-directed Mutagenesis
YANG Sheng,HUANG He,LI Shi-Yun,YE Yu-Zhen,WAN Lin,ZHANG
Feng-Wen,YUAN Zhong-Yi*
( Shanghai Institute of Biochemistry,the Chinese Academy of
Sciences,Shanghai 200031,China )
Abstract To improve
the stability of penicillin G acylase(PGA) from Bacillus megaterium, a
three-dimensional model of B.megaterium PGA was constructed based on
crystal structure of penicillin G acylase from E.coli using PMODELING
program. The mutation of Lys at β427 and 430 to Ala was predicted to enhance
the stability of PGA in acidic or organic solvent environment. The results
showed that 2 mutant PGA had similar specific activity and Km as the
parent PGA. Their optimum pH dropped 0.5 pH units. The stability of Lys430Ala
was enhanced obviously at pH 5.2. The half lives of Lys427Ala and Lys430Ala
were improved by 60 % and 166 %, respectively, in comparison with the parent
PGA. �お�
Key words penicillin G acylase；site directed mutagenesis；stability
*Corresponding author：Tel,86-21-64374430-289；Fax,86-21-64338357；e-mail,[email protected]