酪蛋白水解物的类蛋白反应修饰及其产物ACE抑制活性特征  

Modification of Casein Hydrolysate by Alcalase-catalyzed Plastein Reaction and ACE-inhibitory Activity of Modified Products

作　　者：孙辉[1] 赵新淮[1] 

机构地区：[1]乳品科学教育部重点实验室,东北农业大学,黑龙江哈尔滨150030

出　　处：《食品科学》2011年第19期60-65,共6页Food Science

基　　金：国家自然科学基金项目(30972132);黑龙江省高等学校科技创新团队建设计划项目(2010td11)

摘　　要：采用碱性蛋白酶水解酪蛋白,制备水解度为10.9%、IC50值为52.6μg/mL的酪蛋白水解物,并利用响应面法优化碱性蛋白酶催化的类蛋白反应修饰条件。修饰反应时间固定为6h时,适宜的条件为酶添加量3.1kU/g pro、底物质量浓度50g/100mL、反应温度25℃。制备9个修饰程度不同的修饰产物,结果显示:修饰产物ACE抑制活性均提高,并且活性最高的修饰产物的IC50降低至14.9μg/mL。该修饰产物离心分级后,上清液部分和沉淀部分的ACE抑制活性分别低于和高于修饰产物,表明沉淀部分是提高ACE抑制活性的主要原因;Tricine-SDS-PAGE电泳分析表明,修饰产物及沉淀部分有较大分子质量的肽分子生成;该修饰产物和上清液部分、沉淀部分的进一步酶水解处理则显示,酶水解会导致它们的ACE抑制活性降低,但是仍然高于最初的酪蛋白水解物。Casein hydrolysate with a hydrolysis degree of 10.9% and an ACE-inhibitory IC50 of 52.6 μg/mL was prepared by hydrolyzing casein with alcalase and then modified by alcalase-catalyzed plastein reaction.When the reaction time was fixed at 6 h,the optimal reaction conditions were achieved by response surface methodology to be enzyme dosage of 3.1 kU/g protein,reaction temperature of 25 ℃ and substrate concentration of 50 g/100 mL.Nine modified casein hydrolysates with different modification degrees were prepared.The results indicated that each modified casein hydrolysate had enhanced ACE-inhibitory activity.The IC50 of the modified hydrolysate with the highest activity was 14.9μg/mL.This modified hydrolysate was centrifuged into two fractions,a supernatant and a precipitation fraction.The supernatant and precipitation fractions revealed a reduced and enhanced ACE-inhibitory activity when compared with their suspension,suggesting that the precipitation fraction accounted mainly for the improved activity of the modified hydrolysate.Tricine-SDS-PAGE electrophoresis analysis also showed that some new peptides with higher molecular weights were generated in the modified hydrolysate and the precipitation faction.The further enzymatic hydrolysis of the supernatant and precipitation fractions could result in the impairment of ACE-inhibitory activity.

关 键 词：酪蛋白水解物 碱性蛋白酶 类蛋白反应 ACE抑制活性 

分 类 号：TS252.54[轻工技术与工程—农产品加工及贮藏工程]