Optimized-code bull protamine gene was synthesized, the code (CGT) which E. coli. is partial to was substituted for the rare codes(AGA or AGG), the gene was cloned into pGEX-2T to construct expression vector pGEX-2T-PS.

• 利用大肠杆菌偏好的编码精氨酸的密码子CGT将野生型牛精蛋白基因中编码精氨酸的稀有密码子 (AGA或AGG)替换掉 ,通过基因合成得到密码子优化的牛精蛋白基因 ,将其克隆入原核表达载体pGEX 2T ,组装成表达载体pGEX 2T PS。