导　　师： 洪鹏志

学科专业： 083204

授予学位： 硕士

作　　者： ;

机构地区： 广东海洋大学

摘　　要： pH值调节法（pH-shifting，酸//碱溶解-等电点沉淀法）是一种新型的动物蛋白质提取方法，在低温偏离蛋白质等电点的极端酸性（pH≤3.0）或极端碱性（pH≥11.0）条件下使蛋白充分溶解，高速离心除去脂肪和不溶性杂质制备可溶性蛋白溶液，然后在等电点条件下使蛋白沉淀并回收，制备鱼分离蛋白（Fish Protein Isolates，FPI）。由于酸//碱法提取蛋白质回收率高、脂肪含量低、环境的污染小、凝胶强度好、色泽较好且具有较好的贮藏稳定性而受到广泛的关注，但提取过程中蛋白质结构和性质变化的研究相对较少，如不同阴阳离子的选择对pH值调节法的影响以及酸碱调节处理对肌球蛋白的结构-功能的影响。 为此，本研究以罗非鱼肉为原料，提取肌球蛋白，探讨pH值调节处理过程中，肌球蛋白分子酸//碱去折叠、等电点和中性调节重折叠过程中分子结构和性质的变化。其主要目的是进一步了解pH值调节处理过程中分子构象的动态变化，完善其基础理论体系，为低值海洋蛋白制备技术体系的建立和新型功能性分离鱼蛋白的开发提供依据。主要研究结果如下： 1.采用pH值调节（pH2.0-5.5、3.0-5.5、11.0-5.5、12.0-5.5）处理制备四种鱼分离蛋白，分别提取其水溶性组分和盐溶性组分，对其组成、溶解性、表面疏水性、总巯基和活性巯基含量、色氨酸荧光光谱、SDS-PAGE等进行检测和分析。结果表明：分离蛋白中盐溶性组分比例高于水溶性组分比例（p<0.05），且碱提蛋白中盐溶性蛋白的比例比酸提蛋白高（p<0.05）,表明碱法更易蛋白的提取；分离蛋白中水溶性组分和盐溶性组分的溶解性均受pH值的影响比较明显，酸提蛋白的溶解性较碱提蛋白的低；与新鲜鱼肉蛋白相比，四种分离蛋白中水溶性组分和盐溶性组分均发生了变性，体系的表面疏水性增加、巯� The pH-shifting is a perfect approach for extracting protein. Fish protein isolates /(FPI/)were extracted at either acidic /(pH≤3.0/) or alkaline /(pH≥11.0/) at low temperature to obtainthe maximum solubility and remove fat and insoluble impurities via high-speedcentrifugation followed by the recovery of precipitated proteins at their isoelectric point.The pH-shifting has received widespread attention for high recovery rate, low fat content,few-environmental pollution, strongly gel intensity, good color and a better storage stability.The study on conformation and physicochemical property in the extraction process ofprotein, however, is rarely. Such as: the degree of influence by pH on the property andstructure of protein; the influence on pH-shifting by different ions; the influence onstructure and functions of myosin by pH-shifting. This paper taking tilapia as raw material, extract myosin and focus on the change ofconformation during unfolding and refolding of protein. The main purpose is to improvethe mechanism of pH-shifting and made it more mature, which will provide a fundamentalresearch for the widespread use of protein. This provides a bass for the processing system’sbuild of the low value marine proteins and development of new function of fish proteinisolates. The primary contents and results in this thesis as shown below: 1. Four protein isolates were prepared by pH-shifting /(pH2.0-5.5、3.0-5.5、11.0-5.5、12.0-5.5/) and extraction of water-soluble and salt soluble components from them. Thecomponent proportion, solubility, surface hydrophobicity, total sulfhydryl and activesulfhydryl content, the fluorescence of the Tyr residues and SDS-PAGE were detection andanalysis. The study showed that the proportion of salt-soluble protein was higher thanwater-soluble protein and the salt-solution extracted by alkali was higher than acid/(p<0.05/), which indicated alkali was easier to extract protein. pH has a significantinfluence on the solubility of water-soluble protein and salt-soluble prote

关 键 词： 罗非鱼 肌球蛋白 调节法 去折叠 重折叠 构象

领　　域： [轻工技术与工程] [轻工技术与工程]