牛链球菌L-(+)-乳酸脱氢酶基因的克隆及在大肠杆菌中表达

Cloning and Expression of the Gene Encoding the L-(+)Lactate Dehydrogenase from Streptococcus bovis in Escherichia coli

利用PCR方法从牛链球菌(Streptococcus bovis)基因组DNA中扩增出了L(+)乳酸脱氢酶基因(ldh),并将其连接到表达载体pSE380上,得到重组质粒pSEldh,将重组质粒转化到大肠杆菌菌株JM109。利用SDS-PAGE分析ldh表达产物的分子量为36KD,重组菌株的乳酸脱氢酶酶活力为168.2U/mL,最适反应温度25℃,最适作用pH为5.0,重组质粒的稳定性达99.9%。

The gene ldh encoding L-（ ＋ ）-lactate dehydrogenase was amplified from genome DNA of Streptococcus boris by PCR. The recombinant plasmid pSE-ldh was constructed by inserting ldh into expression vector pSE380 and then transformed into E. coli JM109. SDS-PAGE showed that the relative molecular weight of the expression product was about 36 kD. The activity of L-（ ＋ ） lactate dehydrogenase of recombinant strain was 168.2 U/mL. The optimal temperature was 25℃ and the optimal pH was 5.0. The stability of the plasmid pSE1dh in E. coli JM109 was 99.9%.