重组人前列腺特异性抗原的原核表达、纯化与鉴定

目的:用分子克隆技术体外制备人前列腺特异性抗原(PSA)重组蛋白,并对其活性进行鉴定。方法:用分子克隆技术从前列腺癌cDNA文库中扩增PSAcDNA,再将cDNA和准备插入的质粒载体PET-12α分别用限制性内切酶NdeⅠ和BamHⅠ消化,然后用T4连接酶将两者连接,序列正确的阳性克隆转染BL21(DE3)大肠埃希菌,诱导表达重组人PSA蛋白,从细菌包涵体中纯化PSA蛋白,再用小剂量胰岛素激活PSA活性,观察活化的PSA是否分解其变色底物S-2586和天然底物精囊蛋白Semenogelin(Sg)。结果:利用原核表达技术得到了重组人PSA,在胰岛素作用下PSA被激活,活性PSA水解其天然底物Sg和变色底物S-2586。结论:用基因克隆方法体外获得的重组人PSA蛋白可表现与天然PSA同样的丝氨酸蛋白酶活性和功能。

Procaryotic Expression,Purification and Identification of Recombinant Human Prostate-specific Antigen

OBJECTIVE: To produce recombinant human prostate-specific antigen (PSA) by molecular cloning technology and to identify its activity. METHODS: The human PSA cDNA and PET-12a vector were digested by NdeI and BamH1 before ligated by T4 ligase. The correct sequence was verified and transformed into high competent E. coli BL21 (DE3). Recombinant PSA was expressed and purified by hydrophobic interaction phenyl Sepharose column and activated by trypsin digestion. Enzymatic activation assay was done by hydrolysis of the substrate S-2586 and semenogelin. RESULTS: Non-active recombinant PSA was digested by trypsin and demonstrated enzyme activity. The activated PSA hydrolyzed S-2586 and its physiological substrate semenogelin (Sg). CONCLUSION: Recombinant pro-PSA can be an active serine protease by trypsin digestion and demonstrate native PSA enzymatic activity.