Lewis U J, Singh R N, Lewis L J, Seavey B K, Sinha Y N
Proc Natl Acad Sci U S A. 1984 Jan;81(2):385-9. doi: 10.1073/pnas.81.2.385.
A modification of prolactin, in which the asparagine at position 31 carries a carbohydrate unit, was isolated from ovine pituitary glands. Sequence and amino acid analyses identified the point of linkage of the carbohydrate. Glucosamine was found in acid hydrolysates, an indication that the carbohydrate is attached through N-acetylglucosamine. The glycosylated prolactin binds to concanavalin A and lentil lectin and is eluted with methyl alpha-D-mannopyranoside. During gel electrophoresis in sodium dodecyl sulfate, the glycosylated hormone migrates as a Mr 25,000 protein; prolactin has a Mr of 23,000. The modified prolactin had a potency of 20 international units/mg, approximately equal to 60% the potency of a reference prolactin preparation when measured by the pigeon crop sac assay. In a radioimmunoassay, the glycosylated form had only 34% the immunoreactivity of ovine prolactin.
从绵羊脑垂体中分离出一种催乳素的修饰物，其中31位的天冬酰胺带有一个碳水化合物单元。序列和氨基酸分析确定了碳水化合物的连接点。在酸水解产物中发现了氨基葡萄糖，这表明碳水化合物是通过N-乙酰氨基葡萄糖连接的。糖基化催乳素与伴刀豆球蛋白A和扁豆凝集素结合，并可用α-D-吡喃甘露糖苷洗脱。在十二烷基硫酸钠凝胶电泳过程中，糖基化激素以分子量为25,000的蛋白质形式迁移；催乳素的分子量为23,000。经修饰的催乳素的效价为20国际单位/毫克，在用鸽嗉囊试验测定时，约相当于参考催乳素制剂效价的60%。在放射免疫测定中，糖基化形式的免疫反应性仅为绵羊催乳素的34%。
