Department of Biochemistry and Nutrition, Central Food Technological Research Institute, Council of Scientific and Industrial Research, Mysore 570 020, India.
Department of Protein Chemistry and Technology, Central Food Technological Research Institute, Council of Scientific and Industrial Research, Mysore 570 020, India.
Carbohydr Polym. 2014 Feb 15;102:615-21. doi: 10.1016/j.carbpol.2013.11.043. Epub 2013 Dec 4.
Pepsin (porcine stomach mucosa, E.C. 3.4.23.1), an acid protease catalyzes the hydrolysis (debranching) of guar galactomannan (GG), a co-polymer of mannose and galactose residues thereby showing its non-specific catalysis towards glycosidic substrates.
Use of non-specific inhibitors, chemical modification agents and peptide mapping of native and GG--bound pepsin upon proteolytic digestion with Staphylococcus aureus V8 protease revealed the involvement of Asp(138) residue in the catalysis, which was confirmed by computational modelling studies.
Here we show a novel mode of catalysis (other than proteolysis) by porcine pepsin with a different active site residue.
胃蛋白酶（猪胃黏膜，EC 3.4.23.1）是一种酸性蛋白酶，可催化瓜尔豆胶（GG）的水解（去支链），GG 是甘露糖和半乳糖残基的共聚物，从而表现出对糖苷底物的非特异性催化作用。
使用非特异性抑制剂、化学修饰剂和对金黄色葡萄球菌 V8 蛋白酶消化后与 GG 结合的天然胃蛋白酶和 GG 结合的胃蛋白酶进行肽图分析，揭示了 Asp（138）残基参与了催化作用，这通过计算建模研究得到了证实。
在这里，我们展示了猪胃蛋白酶通过不同的活性部位残基进行的一种新的（非蛋白水解）催化模式。
