Structure-physicochemical property relationships at molecular levels of seed storage proteins

除一些谷物外，大多数植物种子与大豆一样，含有7S和/或11S球蛋白作为主要的贮藏蛋白。一些作物很可能含有与大豆不同的具有有用特性的7S和/或11S球蛋白，因为它们与大豆蛋白的氨基酸序列同源性为35-80% 1。不同作物贮藏蛋白的理化性质：比较了豌豆、蚕豆、红豆、芸豆、南瓜和本巴拉豆在相同条件下的7S和/或11S的理化性质。我们发现芸豆7S在低离子强度下具有较高的溶解度，而大黄豆11S的热稳定性很低。重组蛋白7S与天然蛋白7S的理化性质比较：红豆和芸豆7S在大肠杆菌中表达。重组7Ss与天然7Ss的理化性质比较表明，碳水化合物部分有助于低离子强度下的溶解度。x射线结晶学：对重组大豆11SA2Bla、豌豆11S、南瓜11S和红豆7S进行结晶处理。除豌豆11S外，其余均有适合x射线结晶学的晶体。我们成功地确定了它们的结构。结构-理化性质关系：本研究得到的所有数据表明，分子表面静电势是低离子强度下溶解度的关键因素。

Most of plant seeds except some cereals contain 7S and/or 11S globulin as major storage proteins in analogy with soybean. It is highly probable that some crops contain 7S and/or 11S globulins having useful properties different from those of soybean, since amino acid seguence identities of them with those of soybean proteins are 35-80%.1.Physicochemical properties of storage proteins of various crops :We compared physicochemical properties of 7S and/or 11S from pea, broad bean, azuki bean, kidney bean, pumpkin and bumbara bean at the same condition as that used for soybean proteins. We found that kidney bean 7S exhibits high solubility at low ionic strength and bumbara bean 11S has very low thermal stability.2.Comparison of physicochemical properties of recombinant and native 7S :Azuki bean and kidney bean 7Ss were expressed in E.coli. Comparison of physicochemical properties of the recombinant and native 7Ss indicated that carbohydrate moiety contributes to solubility at low ionic strength.3.X-ray crystallography :Recombinat soybean 11SA2Bla, pea 11S, pumpkin 11S and azuki bean 7S were subjected to crystallization. All of them except pea 11S gave crystals suitable for X-ray crystallography. We succeeded to determine their structures.4.Structure-physicochemical Property relationship :All the data we obtained in this study indicate that molecular surface electrostatic potential is a kea factor of solubility at low ionic strength.