Purification
and Characterization of Alcaligenes faecalis Penicillin G Acylase
Expressed in Bacillus subtilis
ZHOU Zheng1,
ZHOU Li-Ping1#, CHEN Mei-Juan1$, ZHANG Yan-Liang1
LI Ren-Bao1, YANG Sheng2, YUAN Zhong-Yi1*
( 1 Institute of Biochemistry and Cell
Biology, Shanghai Institutes for Biological Sciences, the Chinese Academy of
Sciences, Shanghai 200031, China;
2 Institute of Plant Physiology and Ecology, Shanghai
Institutes for Biological Sciences, the Chinese Academy of Sciences, Shanghai
200031, China )
Abstract The Alcaligenes faecalis PGA gene
encoding heterodimeric penicillin G acylase (PGA) was cloned and successfully
expressed in Escherichia coli and Bacillus subtilis respectively.
In contrast to E. coli hosts where the enzymes were retained in the
periplasm, B. subtilis cell secreted the recombinant enzyme into the
medium. Contrary to limited expression yield of E. coli (pETAPGA), PGA
extracellularly expressed by B. subtilis (pBAPGA) and B. subtilis
(pMAPGA) reached the highest yield of 653 u/L. This yield increased 109-fold
higher than the native expression of A. faecalis CICC AS1.767. The
enzyme was fractionated with (NH
purified by DEAE-Sepharose CL-6B with a yield of 81%. The purified enzyme had a
specific activity of 1.469 u/mg. Furthermore, some enzyme characteristics, such
as the pH and temperature optimum, the stability against organic solvent and
the ratio of cepholexin synthesis to hydrolysis were determined. By
overexpressing A. faecalis PGA in B. subtilis and purifying
secreted enzyme from culture medium one could readily obtain a large amount of
an alternative source of PGA.
Key
words
penicillin G acylase; Alcaligenes faecalis; Bacillus subtilis
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