中文摘要：

小清蛋白（parvalbumin，vv）是鱼类的主要过敏原，为分析淡水鱼PV的序列及结构特征，采用RT-PCR方法，从鲫和鳜肌肉中分别克隆得到2种小清蛋白的基因序列。生物信息学分析结果显示，4种基因的序列长度均为330bp，编码109个氨基酸残基，推导分子量在11．6ku左右，等电点为4．45-4．69。氨基酸序列分析表明，克隆得到的这4种PV序列均含有丙氨酸-14、亮氨酸．16、半胱氨酸．19、苯丙氨酸．67、谷氨酰胺-69以及苏氨酸．79等β型PV特征性残基序列，表明克隆的目的基因均为β型PV。鲫的2种PV序列相似性为80．73％，鳜的2种PV的序列相似性为83．49％。对克隆得到的PV序列进行空间结构分析显示，这4种PV序列均含有3个螺旋一松弛一螺旋结构，即EF一手型结构，其中靠近c端功能域的两个手型结构为Ca^2＋结合位点。

英文摘要：

Parvalbumin （PV） is the major allergen of fish species. So far, research concerning fish allergy has been focused mainly on marine fish. China is the largest consumer and producer of freshwater fish in the world, and many people suffered from allergy when consuming freshwater fish. Therefore, figuring out the molecular characters of PV from freshwater fish would be important. In this study, four gene sequences of PV isoforms were amplified and cloned from crucian carp and mandarin fish by RT-PCR, with two genes from each species. All the four genes were 330 bp in length, encoding 109 amino acid residues. The deduced molecular weight of them was approximately 11.6 ku, and isoelectric points were 4.45-4.69. The existence of amino acid residues of Ala-14, Leu-16, Cys-19, Phe-67, Gln-69 and Thr-79 suggested that all the sequences belonged to 13-PV. The identity between the two sequences of crucian carp was 80.73 %, and was 83.49 % in mandarin fish. The identity between PVs from different fish species was higher than 75 % and the sequences of Ca2＋ binding sites were highly conserved. Phylogenetic tree based on some PV amino acid residues revealed that PVs are clustered into two major clades, teleost fish and other vertebrates. PVs of teleost were clustered into orthologous groups, suggesting duplication of the PV genes before the speci- ation of teleost while after the speciation of fish. The tertiary structures of these four PVs were constructed using SWISS-MODEL. They all contain three helix-loop-helix motifs named EF-hand. Two domains next to the C terminal were Ca2＋ binding sites. These results may provide a molecular basis for further study on the allergen of fish PVs.