腺苷蛋氨酸合酶在大肠杆菌中的异源表达及发酵条件的优化

denosylmethionine (SAM) plays a vital role in the organisms' metabolic activity as an important intermediate metabolite. It has widely used mainly in pharmaceutical industry involing the therapies for liver, nervous systems, osteoarthritis and sexual dysfuction. To heterologously express adenosylmethionine synthase in Escherichia coli, the adenosylmethionine synthase gene sam2 from S. cerevisiae BY4741 was used to carry out codon optimization according to the codon bias of Escherichia coli. We constructed recombinant plasmids pET-28a(+)-sam2 and pET-3b(+)-sam2 and introduced into the host strains E. coli BL21(DE3) and E. coli Rosseta (DE3) to obtain the recombinant bacterium. The recombinant strain E. coli BL21/ pET28a(+)-sam2 has higher enzymatic activity of 0.184 U/mL. The recombinant strain E. coli BL21/ pET-28a(+)-sam2 was used as original strain to screen the culture medium and optimize the IPTG induction concentration and induction time of to improve enzymatic activity. The results showed that TB medium was the optimum medium and the final concentration of IPTG was 0.1 mmol/L and after inducting 24 h, the enzyme activity of the recombinant adenosylmethionine synthase reached 0.245 U/mL. Our findings open the possibity practical application for the inexpensive production of adenosylmethionine by enzymatic method.