中文摘要：

过氧化物还原酶6具有谷胱甘肽过氧化物酶和磷脂酶A2的双重活性，在机体抗氧化保护及肺表面活性物质代谢中具有重要的作用。研究克隆和分析了褶纹冠蚌Prx6（CpPrx6）基因的cDNA序列特征。结果表明CpPrx6基因的cDNA全长1617bp；其中5＇端非翻译区为71bp，3＇端非翻译区为889bp，开放阅读框为657bp，可以编码218个氨基酸。CpPrx6氨基酸序列与其他已知贝类Prx6的同源性为70％-72％。CpPrx6蛋白含有1-Cys型Prx共有的保守催化中心“PVCTTE”和脂肪酶基序“GKSWA”，三级结构中包含6个0α螺旋、12个13折叠，催化中心位于第5个α螺旋内。CpPrx6基因在褶纹冠蚌血细胞、外套膜、闭壳肌、肝胰腺、鳃等组织中均有表达，其中鳃的表达量最大。嗜水气单胞菌刺激后6h和12h时CpPrx6在肝胰腺中的表达量明显增加（6h，P〈0．05；12h，P〈0．01），在血细胞和鳃组织中12h的表达量增加，24h时恢复到正常水平。将CpPrx6基因亚克隆到pET-32a（＋）质粒中构建了重组质粒，SDS．PAGE分析发现重组质粒在大肠杆菌DE3中获得了表达。

英文摘要：

Peroxiredoxin 6 has glutathione peroxidase and phospholipid enzyme A2 double activity and plays an impor tant role in antioxidant protection and metabolism of lung surface-active material. Cristaria plicata is one of the most important freshwater mussels for pearl production in China. In this study, a Prx6 homologue - CpPrx6 in Cristaria pli cata, was cloned by utilizing reverse transcriptase polymerase chain reaction and rapid amplification of the cDNA ends. A phylogenetic tree was constructed based on the amino acid sequence of CpPrx6 using neighbor-joining method and MEGA 4.1 software. The three dimensional structure of CpPrx6 was constructed using the Swiss-model. The expression pattems, both in tissues and towards microorganism A. hydrophila stimulation, were then characterized by real-time fluorescence quantitative PCR. The results showed that the full length cDNA of CpPrx6 contained a 5＇- untranslated region （UTR） of 71 bp, an open reading frame of 657 bp that encoded 218 amino acids, and a 3＇-UTR of 889 bp with a 29 bp polyadenylic acid tail. The predicted molecular mass and estimated isoelectric point （pI） of CpPrx6 were 24.24 kD and 6.33, respectively. No signal peptide, the transmembrane region, mitochondria, lysosomes, peroxisomes and nuclei localization sequence were found and contained 1 potential N-linked glycosylation site （N9FTA） in CpPrx6, which suggested that it is a cytosolic protein. The deduced amino acid sequence of CpPrx6 shared 70%-72% overall similar ity with known Molluscan Prx6. The conserved peroxidase catalytic center ＂PVCTTE＂ and a lipase motif ＂GKSWA＂ were observed in the sequence, the tertiary structures of CpPrx6 contained 6 a-helixes and 12 β-sheets, the catalytic center ＂PVCTTE＂ located in fifth a-helix, three conserved residues His22, Asp134 and Ser28 together formed the cata- lytic center of the phospholipase A2, indicating that it was a member of 1-Cys Prx. Phylogenetic analyses showed that CpPrx6 sequence clustered together with the other Mollus