花生球蛋白和伴球蛋白的功能特性及构象研究

Functional and Conformational Properties of Arachin and Conarachin

摘要:

本文对花生球蛋白与伴球蛋白的结构和功能特性进行了分析和比较。结果表明，花生球蛋白在等电点附近（pH 4.5~6.0）比伴球蛋白具有更高的溶解性，而在偏离等电点时其溶解性低于伴球蛋白，伴球蛋白的乳化活性指数（70~180 m2/g）和起泡能力（36~57%）显著高于花生球蛋白的乳化活性指数（60~130 m2/g）和起泡能力（19~33%）（P<0.05），伴球蛋白所形成热凝胶的弹性模量值(G’)约为花生球蛋白的5倍。花生球蛋白的变性温度Td（104.84 ℃）及焓变值ΔH（13.78 J/g）显著高于伴球蛋白的变性温度（89.47 ℃）与焓变值（8.11 J/g）（P<0.05）；花生球蛋白分子表面的巯基（SH）较少，大部分巯基包裹于球蛋白分子内部，而伴球蛋白中大部分巯基暴露于分子的表面。荧光光谱分析表明，伴球蛋白比花生球蛋白具有更疏松的三级结构和更高的界面活性。

Abstract:

A comparative study was made on functional and conformational properties of arachin and conarachin isolated by ammonium sulfate. Conarachin had the higher solubility than arachin except at near pI (pH 4.5~6.0). And conarachin had better emulision ability index (70~180 m2/g) and foam capacity (36~57%) than arachin (60~130 m2/g and 19~33%). The G’ of conarachin was 5 times higher than that of arachin. Arachin had higher denaturation temperature (104.84 ℃and ΔH value 13.78 J/g) than conarachin (89.47 ℃ and 8.11 J/g) (P<0.05). Most of free SH of arachin was buried in the interior, but located at the surface of conarachin.. Compared with conarachin, arachin had more compacted tertiary conformation and lower surface hydrophobicity.