Molecular Cloning and Expression of S-Adenosylmethionine Synthetase Gene of Escherichia coli

Kb DNA fragment encoded S-adenosylmethionine synthetase was amplified from E. coli JM 10９ by PCR. This fragment was inserted into Nde I/BamHI sites of pET11c which is a highly-expressed vector. The recombinant plasmids were transformed into host strain E. coli BL21(DE3). With SDS-PAGE and TLC, it was proved that S-adenosylmethionine synthetase was 58.3% of the total soluble proteins of recombinant strain. The results of enzyme assays showed that the activity of recombinant strain was 7 times as high as that of the host.