中文摘要：

采用RT-PCR和3′RACE技术,首次从乌鳢胃组织中克隆了一种胃蛋白酶原基因。测序结果表明,该基因开放阅读框全长1086bp编码361个氨基酸,递交GeneBank数据库,获得登录号为GQ303143。系统进化关系分析表明,该乌鳢胃蛋白酶原氨基酸序列与鳜鱼类的胃蛋白酶原A2亲缘关系最近,从而推测本研究克隆的乌鳢胃蛋白酶原属于胃蛋白酶原A2类。采用生物信息学的方法和工具预测了该乌鳢胃蛋白酶原的理化参数及其高级结构,结果表明,该乌鳢胃蛋白酶原的相对分子量为38.8kDa,理论等电点为4.56。采用同源建模法建立了乌鳢胃蛋白酶原的三维结构模型,预测了其活性位点及6个必需半胱氨酸残基的位置。该研究结果为进一步研究乌鳢胃蛋白酶的结构和功能关系奠定了基础。

英文摘要：

In this study, the pepsinogen gene was first cloned from the stomach of freshwater fish snakehead （Channa argus） by RT-PCR and 3′RACE. The result of sequencing indicated that the pepsinogen gene had an open reading frame of 1086bp, encoding 361 amino acids. The pepsinogen gene had been deposited in the GenBank Data Libraries under the ac- cession number of GQ303143. The NJ phylogenetic tree of vertebrates based on the amino acid sequences of pepsinogens showed that C. argus pepsinogen was closest to the pepsinogen A2 of Siniperca chuatsi, which suggested that the pepsi- nogen of C. argus might be a pepsinogen A2. Bioinformatics analysis predicted that the C. argus pepsinogen had a theo- retical molecular mass of 38.8kDa with a theoretical pI of 4.56. In addition, the three-dimensional structure of the pepsi- nogen was constructed by homology modeling to predict its active sites and six essential cysteine residues. This study pro- vides novel insights into the relationship between structure and function of the pepsinogen.