Abstract: A proinsulin analog gene (B^-3CA) has been constructed in which the coden of C-terminal three residues of B chain were deleted, and was recombined with pBV220, an expression vector with P_R P_Lpromoter, Because of the difficulty to remove the N-terminal initiator methionine residue of recombinant protein in E.coli, another mutegenesiswas made by PCR to insert a Lys coden between the coden of initiator methionine and of the first residue Phe. After expressed in E.coli with the level accounting for 12% of total bacterial protein, the product was purified and processed to Desterpeptide of C-terminal human insulin which remained only 49% radioimmuno activity and 45% receptor binding activity of porcine insulin.

Key words: Des-terpeptideof C-terminal human proinsulin, mutegensis, expression

摘要： 用改进的寡核苷酸诱导突变法将人胰岛素原基因（BCA）删除编码B链羧端三肽（28～30残基）的碱基片段，得到去B链羧端三肽胰岛素原的基因(B^-3CA)。为了便于表达产物的蛋白质后加工，又用PCR的方法在B链N端起始Met与Phe密码子之间增加了编码Lys的3个碱基，得到改造后基因LB^-3CA。将LB^-3CA克隆到表达质粒pBV220上，在大肠杆菌系统中热诱导表达，表达率为12%。表达产物经蛋白质后加工，得到的去Ｂ链羧端三肽人胰岛素（DTEIB28～30人胰岛素）其受体活性和放免活性分别是猪胰岛素的45%和49%。

关键词: 去B链羧端三肽人胰岛素, 基因突变, 表达