低值鱼天然肌球蛋白分子的定向修饰及其热稳定性机理研究

项目名称： 低值鱼天然肌球蛋白分子的定向修饰及其热稳定性机理研究

项目编号： No.31301437

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 农业科学

项目作者： 刘建华

作者单位： 浙江工业大学

项目金额： 24万元

中文摘要： 糖基化定向修饰蛋白质提高功能特性是食品领域的研究热点。前期实验表明，具有多支链、特异亲水基团和适度分子量的魔芋葡甘露低聚糖（KOG）定向修饰低值鱼肌球蛋白（Ms）后热稳定性极大提高，但定向修饰和热稳定性机理尚不清楚。本项目拟制备KOG定向修饰Ms获得Ms-KOG；通过测定赖氨酸含量和取代度确定定向修饰位点和量，分析Ms-KOG等电点、分子量、表观黏度变化，阐明定向修饰机理；采用现代仪器分析法表征Ms-KOG微观结构、Ms一级、二级、三四级结构变化；测定Ms-KOG变性温度、吉布斯自由能、熵和焓的热力学特性变化，确定定向修饰后Ms能垒（ΔGglyco）增加途径（熵变或焓变）；结合空间结构和热力学特性变化进行多因素相关性分析，确定Ms熵变或焓变发生时的空间结构（折叠态或去折叠态），揭示Ms定向修饰热稳定性机理。本项目将为糖基化定向修饰机理、蛋白质-多糖结构和热稳定性有效调控等研究提供理论借鉴。

中文关键词： 肌球蛋白；魔芋葡甘露低聚糖；糖基化反应；热稳定性；机理

英文摘要： Protein directional modification based on glycosylation for enhanced functional properties has been widely studied recent years in food industry. In our previous study, konjac oligo-glucomannan (KOG) with multi-branched chains, special hydrophilic group and moderate molecular weight was prepared to directionally modify myosin (Ms) from low-quality fish, and the result showed that the thermal stability of Ms was greatly increased. However, the mechanisms of directional modification and thermal stability were unclear. The present study prepares KOG, which is used to directionally modify Ms to form Ms-KOG. The content of lysine and degree of substitution were determined to verify the sites and amount of directional modification, and the physicochemical properties including isoelectric point, molecular weight and apparent viscosity were analyzed, for elucidating the mechanism of directional modification. The spatial structure consisting of microstructure of Ms-KOG, primary, secondary, tertiary and quaternary structure of Ms were characterized. Thermodynamic properties including denaturation temperature, Gibbs free energy, entropy and enthalpy of Ms-KOG were determined, in order to study the increasing way (change in entropy or enthalpy) of energy barrier (ΔGglyco). Based on the multi-factors correlation analysis, th

英文关键词： myosin (Ms)；konjac oligo-glucomannan (KOG)；glycation；heat stability；mechanism