大分子拥挤环境下多糖对蛋白肽的修饰研究

Properties of Protein Peptides Modified by Dextran in Macromolecular Crowding Condition

摘要:

采用胃蛋白酶适度水解大豆分离蛋白得到蛋白肽，在大分子拥挤环境下通过Maillard反应制备蛋白肽-葡聚糖共价复合物（Hydrolated Soy Protein Isolated-Dextran Conjugates，HDC），采用十二烷基磺酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）技术证实大豆7S球蛋白和葡聚糖发生了共价结合，并通过乳化剪切机、荧光分光光度计、差示扫描量热仪和粒度分布仪等对其接枝度、溶解性、热稳定性、抗氧化性和乳化性能进行系统分析。结果表明：大分子拥挤环境下大豆水解蛋白肽-葡聚糖60 ℃反应4 h就可以形成较高接枝度的共价复合物，溶解性较大豆分离蛋白（Soybean protein isolated，SPI）和大豆分离蛋白-葡聚糖（Soybean Protein Isolated-Dextran Conjugates，SDC）有所提高，热稳定性好，HDC的自由基清除率明显高于大豆水解蛋白和它与葡聚糖的混合物，达到66.39%，且羟自由基清除率高于维生素C，HDC的乳液粒径最小并具有优越的乳化稳定性。

Abstract:

In this work, properties of protein peptides modified by dextran in macromolecular crowding condition in liquid system were investigated. The result indicated that the conjugate prepared by protein peptides and dextran reacting at 60℃ for 4h had superior function on the grafted degree, thermal stability, oxidation resistance and emulsification. First, pepsin was introduced for enzymolysis of soybean protein isolated, preparing the glycopeptide. Glycopeptide-dextran covalent conjugate was prepared via Maillard reaction in macromolecular condition. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to confirm the formation of covalent conjugate of 7S-dextran. In macromolecular crowding conditions, the Maillard reaction and enzymatic were combined for the protein glycosylated reaction, the enzymatic can greatly shorten the chemical modification reaction time. The pepsin give a driving force to unfold the tertiary structure of protein, promoting the exposure ofε-amino groups and covalent attachment to the dextran.