Quality-structure relationships of soybean storage proteins

本课题旨在阐明大豆贮藏蛋白大豆球蛋白和伴大豆球蛋白的质量-结构关系。我们试图从三个角度来研究这些问题。(1)大豆球蛋白的结构-功能关系：基于我们在本研究之前揭示的结构-功能关系，我们对大豆球蛋白进行了修饰以改善其功能性质。大多数修饰的大豆球蛋白具有比天然大豆球蛋白更好的功能性质，表明我们揭示的结构-功能关系是合理的。(2)伴大豆球蛋白的结构-功能关系：构建了伴大豆球蛋白的组成亚基α、α '和β的大肠杆菌表达系统。所有重组亚基形成具有适当构象的同源三聚体。这些重组亚基的功能特性的分析揭示了决定其溶解性，表面疏水性，热稳定性，乳化能力和热诱导的协会的结构因素。(3)重组和天然大豆球蛋白和伴大豆球蛋白的X射线晶体学：将使用B.coli表达系统制备的重组前大豆球蛋白A1 aB 1 B b、A3 B4和伴大豆球蛋白β，以及从含有由一种亚基组成的大豆球蛋白或伴大豆球蛋白的突变大豆制备的天然大豆球蛋白A3 B4和伴大豆球蛋白β结晶用于X射线晶体学。在2.1-2.8 * 水平上解析了它们的三维结构。这些结果有助于在分子水平上研究大豆球蛋白和伴大豆球蛋白的质量-结构关系。

Object of this project is to elucidate quality-structure relationships of soybean storage proteins glycinin and conglycinin. We approached to investigate these from three viewpoints.(1) Structure-function relationships of glycinin : We modified glycinin to improve its functional properties based on the structure-function relationships revealed by us prior to this study. Most of the modified glycinins exhibited better functional properties than those of the native glycinin, indicating that the structure-function relationships revealed by us are reasonable.(2) Structure-function relationships of conglycinin : F.coli expression systems for the constituent subunits alpha, alpha' and beta of conglycinin were constructed. All recombinant subunits formed homotrimers having the proper conformation. Analyses of functional properties of these recombinant subunits revealed structural factors determining their solubilities, surface hydrophobicities, heat-stabilities, emulsifying abilities and heat-induced association.(3) X-ray crystallography of recombinant and native glycinin and conglycinin : Recombinant proglycinin A1aB1b, A3B4 and conglycinin beta prepared using B.coli expression systems, and native glycinin A3B4 and conglycinin beta prepared from mutant soybeans containing glycinin or conglycinin composed of a kind of subunit were crystallized for X-ray crystallography. Their three dimensional structures were solved at 2.1-2.8 * levels. These elucidation surely contribute to investigate quality-structure relationships of glycinin and conglycinin at a molecular level.