Graduate School of Agriculture, Kyoto University, Kitashirakawa, Kyoto 606-8502, Japan.
Graduate School of Agriculture, Kyoto University, Kitashirakawa, Kyoto 606-8502, Japan.
Food Chem. 2014 Jul 15;155:192-8. doi: 10.1016/j.foodchem.2014.01.047. Epub 2014 Jan 24.
The α polypeptide of the 13S globulin subunit of common buckwheat is the counterpart of the major allergenic β polypeptide. Trypsin digestibility varies between variants of the α polypeptide with and without a tandem repeat insert. To evaluate the intra-species diversity of 13S globulin, the comprehensive screening of a genomic DNA library was performed, resulting in the isolation of 14 and 3 genes for Met-poor and Met-rich subunits, respectively. Although most tandem repeat units were 45 bp in length, the two-repeat gene Glb2B and all one-repeat genes contained an additional 3 bp. Secondary structure predictions and polyacrylamide gel electrophoresis demonstrated that the sense strand of Glb2B-CCG, the additional 3 bp-deletion clone of Glb2B, formed a more rigid secondary structure than that of the wild-type. Thus, the large intra-species variation of 13S globulin revealed in this study and its diversification might be attributable to the unique nature of the tandem repeat sequences.
普通荞麦 13S 球蛋白亚基的 α 多肽是主要过敏原 β 多肽的对应物。具有串联重复插入和不具有串联重复插入的 α 多肽之间的胰蛋白酶消化率不同。为了评估 13S 球蛋白的种内多样性，对基因组 DNA 文库进行了全面筛选，分别分离出 Met 贫乏和 Met 丰富亚基的 14 和 3 个基因。尽管大多数串联重复单元的长度为 45bp，但两个重复单元基因 Glb2B 和所有一个重复单元基因都含有另外的 3bp。二级结构预测和聚丙烯酰胺凝胶电泳表明，Glb2B-CCG 的有义链，即 Glb2B 的额外 3bp 缺失克隆，形成了比野生型更刚性的二级结构。因此，本研究中揭示的 13S 球蛋白的大种内变异及其多样化可能归因于串联重复序列的独特性质。
