中文摘要：

利用大肠杆菌表达系统，表达猪源羧肽酶原B蛋白包涵体，并对包涵体的体外复性条件进行优化。对猪源羧肽酶原B基因进行设计，优化稀有密码子，并将基因片段插入到pET28a载体中，构建表达质粒pET28a—proCPB，并转化人BL21（DE3）中。通过乳糖诱导表达得到包涵体。通过检测酶的比活力来考查复性液的pH、蛋白终浓度、氧化还原对比例、复性时间、复性温度对复性程度的影响。最终确定的体外稀释复性条件为：复性液成份为100mmol／L Gly—NaOH、pH=9．5、GSH与GSSG的比例为1：0．8（GSH为1mmol／L）、蛋白终浓度为200μg／ml、复性温度为25℃、复性时间24h。通过检测，复性液中酶的比活力为11．7u／mg，经过DEAE纯化后酶的比活力可达到73u／mg。

英文摘要：

To express the inclusion body of procarboxypeptidase B in E. coli expression system and to optimize conditions of renaturation of the inclusion body, synthetic porcine-derived procarboxypeptidase B gene,of which the rare codon was substituted, was inserted into pET28a and then transformed into BL21（DE3）. Inclusion body was obtained in the inducement of lactose. Renaturation conditions, including pH value, temperature, time, protein concentration, and the ratio of GSH and GSSG were optimized. After optimizing,the finalized conditions of renaturation are. 100 mmol/L Gly-NaOH pH value 9.5, GSH ： GSSG=1 ： 0. 8, 25℃, renaturation time is 24h, the protein concentration is 200μg/ml. The specific activity was 11.7 u/mg after the dilution method and the specific activity achieved 73 u/mg after purification with DEAE.