A1型和A2型β-酪蛋白分离纯化及其消化特性  

Isolation, Purification and Digestion Characteristics of A1 and A2 β-Casein

作　　者：刘铭 鲁杏茹 李笑 赵倩玉 姜毓君[1] 杨鑫焱 满朝新[1] Liu Ming;Lu Xingru;Li Xiao;Zhao Qianyu;Jiang Yujun;Yang Xinyan;Man Chaoxin(Key Lab of Dairy Science,Ministry of Education,College of Food Science,Northeast Agricultural University,Harbin 150030)

机构地区：[1]东北农业大学食品学院乳品科学教育部重点实验室,哈尔滨150030

出　　处：《中国食品学报》2024年第11期107-117,共11页Journal of Chinese Institute Of Food Science and Technology

基　　金：黑龙江省“百千万”工程科技重大项目(2021ZX12B01-03)。

摘　　要：β-酪蛋白作为牛乳中重要的组成成分之一,具有较高的营养价值。由于基因突变,β-酪蛋白出现多种变体形式,目前最常见的基因型是A1型和A2型。A1型和A2型变体因第67位单一氨基酸的差异,而影响蛋白质的结构和消化特性。本研究首先利用等电点沉淀法从A1普通牛奶和A2牛奶中提取酪蛋白,然后通过阴离子交换色谱和聚丙烯酰胺凝胶电泳方法对β-酪蛋白进行提纯和鉴定,最后构建体外消化体系分析A1型和A2型β-酪蛋白消化产物特性。结果表明,分离纯化的A1型和A2型β-酪蛋白的质量浓度分别为0.58 mg/mL和0.64 mg/mL,纯度分别为和92.45%和94.21%。经体外模拟胃肠消化,A2型β-酪蛋白消化率在4.0 h时达到94%,而A1型β-酪蛋白5.0 h时才达93.47%。随着胃肠消化时间增加,A2型β-酪蛋白粒径逐渐降低,被分解为小于100 nm的物质,而A1型β-酪蛋白粒径仍集中在100~500 nm较大范围。随消化的进行,必需氨基酸含量逐渐增加,在进入肠消化阶段水解度迅速上升,且β-折叠结构含量降低,无序结构增多,说明A2型β-酪蛋白较A1型β-酪蛋白可能更有助于人体胃肠道消化。As one of the important components of milk,β-casein has high nutritional value.Due to genetic mutations,beta-casein appears in many variant forms,with the most common genotypes currently being A1 and A2.The A1 and A2 variants affect the structure and digestion of the protein due to differences in the single amino acid 67th.In this study,casein was first extracted from A1 and A2 milk by isoelectric point precipitation,and thenβ-casein was purified and identified by anion exchange chromatography and polyacrylamide gel electrophoresis.Finally,a digestive system was constructed to analyze the properties of A1 and A2β-casein digestive products.The results showed that the mass concentration and purity of A1 and A2β-casein were 0.58 mg/mL and 0.64 mg/mL,respectively,and 92.45%and 94.21%,respectively.After simulated gastrointestinal digestion in vitro,the digestibility of A2β-casein reached 94%at 4.0 h,while that of A1β-casein reached 93.47%at 5.0 h.With the increase of gastrointestinal digestion time,the particle size of A2β-casein gradually decreased and was decomposed into substances less than 100 nm,while the particle size of A1β-casein was still concentrated in the larger range of 100-500 nm.With the progress of digestion,the content of essential amino acids increased gradually,and the degree of hydrolysis increased rapidly during enteric digestion,and the content ofβ-fold structure decreased,and the disordered structure increased.These results suggested that A2β-casein may be more conducive to gastrointestinal digestion than A1β-casein.

关 键 词：A2型β-酪蛋白 模拟消化 消化产物 消化特性 

分 类 号：TS252.1[轻工技术与工程—农产品加工及贮藏工程]