牛血清白蛋白的同源模建与结构解析

Homology modeling and analysis of three-dimension structure of bovine serum albumin

鉴于蛋白质数据库(PDB)中尚无牛血清白蛋白(BSA)这一重要模式蛋白物的结构信息,本文采用同源模建的方法,基于BSA和人血清白蛋白(HSA)的高序列同源性(76．52%),以HSA与血红素(heme)复合物(1n5u)为模版,应用Modeller8．0模拟软件,完成了BSA的结构解析：其高级结构呈心形,由3个相似的结构域组成,每一结构域由10个螺旋片段构成,顺次包含2个亚域A、B；分子中共有35个Cys残基,17对二硫键,形成8对双二硫桥,并构成9个环；二级结构主要为α-螺旋,占67%,无β-折叠,其余为舒展而柔顺的转角。上述结构信息可为涉及BSA的各项理论研究提供重要的基础数据。

The structure information of bovine serum albumin （BSA）, a common mode protein, has not been available in protein data bank （PDB）. Due to 76.52% of amino acid sequence homology between BSA and HSA, the three-dimension structure of BSA is built up based on homology modeling method by using Modeller 8.0 and taking the complex of HSA and heme（lnSu） as a template. The heart-shaped BSA consists of three structurally homologous domains, and each domain formed by 10 helices is divided into subdomian A and B. There are 35 cysteine residues on nine loops （L1-L9） in BSA molecule, 34 of which form 17 disulfide linkages, and 16 of these form 8 double disulfide bridges. The secondary structure of BSA is predominant α-helix （67%） but without beta-sheets, and the remaining polypeptides as coils occur in turns and extended or flexible regions between subdomains. The above structure data provide important references for variously theoretical research concerned BSA.