大米镉结合蛋白的凝胶层析纯化及生化性质

Purification and biochemical properties of cadmium binding protein from rice

中文关键词:  大米镉结合蛋白  纯化  凝胶层析  氨基酸组成

英文关键词:rice cadmium binding protein  purification  gel chromatography  amino acid composition

中文摘要:

      目的 研究大米镉结合蛋白(Rice cadmium-binding protein,RCBP)的纯化及生化性质,探讨RCBP的形成机理。方法 采用Sephedex G-75凝胶层析从乙醇沉淀的大米蛋白(Ethanol precipitation protein, EP) 中纯化RCBP,SDS-PAGE鉴定RCBP的纯度及测定分子质量,氨基酸自动分析仪、FTIR分析RCBP的氨基酸组成及二级结构。结果 凝胶层析纯化得到组分b(目标RCBP),组分b为纯度均一的RCBP,分子质量约为32 KDa。组分b中疏水性氨基酸占56.76%、芳香族氨基酸占19.41%,是一类富含疏水性氨基酸和芳香族氨基酸的镉结合蛋白。组分b中N-H相对于C=O以反式构型存在,二级结构只含有β-折叠和β-转角。结论 镉通过疏水氨基酸或芳香族氨基酸的特征基团与大米蛋白结合形成RCBP。

英文摘要:

      ABSTRACT: Objective To investigate the purification and biochemical properties of cadmium binding protein from rice and binding mechanism between cadmium and rice protein. Methods Rice cadmium-bining protein (RCBP) was purified from ethanol precipitation protein in rice using gel chromatography. The purity, molecular weight, amino acid composition, and secondary structure of RCBP were analyzed using SDS-PAGE, amino acid automatic analyzer, and FTIR. Results Fraction b (objective RCBP) with uniform purity and 32 kDa of molecular weight was collected from elution buffer of ethanol precipitation protein in rice, and hydrophobic amino acids and aromatic amino acids in fraction b were accounted for 56.76% and 19.41%, respectivly. Moreover, β-sheet and β-turn were mainly secondary structures infraction b, and also existed N-H relative to C=O only in the form of trans-configuration. Conclusion The formation of RCBP was through binding between cadmium and characteristic group of hydrophobic or aromatic amino acids in rice protein.