蛋白核小球藻中3种碳酸酐酶亚型的分析

摘要

选取蛋白核小球藻（ Chlorella pyrenoidosa）中不同碳酸酐酶亚型（α-CA、β-CA、γ-CA）基因，对其编码蛋白的理化性质、跨膜结构域、信号肽及蛋白高级结构进行了分析和预测。结果表明蛋白核小球藻α-CA、β-CA和γ-CA蛋白分子量分别为28.9 kDa、34.9 kDa和24.8 kDa，均为酸性、微亲水和脂溶性蛋白。α-CA可以检测到强的跨膜结构和信号肽区域，推测为胞外CA。β-CA和γ-CA无可信的跨膜结构域和信号肽区域，推测β-CA可能位于细胞质或叶绿体基质中，而γ-CA位于线粒体基质中。 CA蛋白的二级结构预测结果表明α-CA中无规则卷曲所占百分比最高（64.66％），β-CA中α螺旋和无规则卷曲所占百分比分别为44.76％和44.13％，而γ-CA中α螺旋和无规则卷曲含量分别为39.48％和40.34％。三级结构预测分析表明α-CA折叠较松散，β-CA、γ-CA折叠程度较紧密，且γ-CA具有反复折叠的结构。%In this paper, three kinds of CA genes like(α-CA, β-CA and γ-CA) were selected from Chlorella pyrenoidosa, and the physical and chemical properties, transmembrane domain, signal peptide, secondary and tertiary structures of CA isoforms were predic-ted through bioinformatics tools.The results showed that the molecular weights ofα-CA,β-CA and γ-CA were 28.9 kDa, 34.9 kDa and 24.8 kDa, respectively.And they were all acidic, slightly hydrophilic and fat-soluble proteins.One signal peptide and a strong transmembrane domain were detected inα-CA, soα-CA was presumed an extracellular CA.There were no credible transmembrane re-gions and signal peptides in theβ-CA and γ-CA sequences.Combined with the subcellular localization results,β-CA might locate in the cytoplasm or chloroplast stroma, whileγ-CA was in the mitochondrial stroma.The results of secondary structure prediction showed that the percentage of random coil inα-CA was highest, which occupied 64.66%.And the proportions ofα-helix and random coil were almost the same as inβ-CA, which were 44.76%and 44.13%, respectively.And the proportions ofα-helix and random coil inγ-CA protein accounted for 39.48%and 40.34%, respectively.The tertiary structure prediction showed that three dimensional structure ofα-CA was loose,β-CA,γ-CA were relatively compact, and theγ-CA was found to hare a repeated folding-structure.