酶法糖基化修饰对酪蛋白体外消化能力的影响

利用转谷氨酰胺酶（transglutaminase，TGase）催化制备壳寡糖（1 kDa）糖基化酪蛋白；十二烷基硫酸钠-聚丙烯酰氨凝胶电泳和反相-高效液相色谱证实糖基化修饰反应的发生；体外消化实验（胃蛋白酶＋胰蛋白酶）分析糖基化修饰反应对酪蛋白消化性的影响。结果表明：TGase成功催化壳寡糖连接到酪蛋白分子上，所制备的糖基化酪蛋白中氨基葡萄糖的导入量为6.86 g/kg；糖基化酪蛋白经体外模拟消化后，其水解度和三氯乙酸可溶性氮均低于酪蛋白对照物，糖基化酪蛋白消化物中出现了更多大分子质量的肽段，研究表明TGase途径糖基化修饰降低了酪蛋白的体外消化能力。

WANG Xiaopeng,ZHAO Xinhuai

Transglutaminase (TGase) was employed to catalyze the preparation of glycosylated casein with chitosan (1 kDa). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and reverse phase-high performance liquid chromatography (RP-HPLC) analysis confirmed the occurrence of glycosylation. In vitro digestion with pepsin plus trypsin was used to evaluate the effect of the glycosylation modification on casein digestibility. The results showed TGase catalyzed the acyl-transfer reaction between casein and chitosan and the amount of glucosamine bound to modified casein was 6.86 g/kg protein. After in vitro digestion, the degree of hydrolysis and trichloroacetic acid-soluble nitrogen (TCA-SN) of glycosylated casein were lower than those of native casein, and more macromolecular peptides were found in the glycosylated casein digest. This study showed glycosylation modification with TGase reduced the digestibility of casein.