鲈鱼生长催乳素的分离纯化与N-末端序列分析

Isolation and purification of somatolactin and its N-terminal amino acid sequence analysis from Japanese sea bass (Lateolabrax japonicus)

生长催乳素（ＳＬ）是生长激素／催乳素家族的一种新的脑垂体蛋白质激素，本研究首次从鲈鱼脑垂体中分离得到．鲈鱼脑垂体在碱性条件下，经葡聚糖凝胶（ＳｅｐｈａｄｅｘＧ－１００）过滤和反相高效液相色谱（ｒｐＨＰＬＣ）分离出纯化的鲈鱼生长催乳素，（ｓｂＳＬ），并与大麻哈鱼生长催乳素（ｓＳＬ）抗体发生特异性的Ｗｅｓｔｅｒｎ免疫印迹交叉反应证实。ＳＤＳ－聚丙烯酰胺凝胶电泳（ＳＤＳ－ＰＡＧＥ）分析，发现鲈鱼生长催乳素分别是由分子量为２３．２×１０３和２８．４×１０３ｕ两种形式组成（后者可能是一种糖基化形式）．根据Ｅｄｍａｎ降解原理，测得鲈鱼生长催乳素的Ｎ－末端１６个氨基酸的序列，它与已知鱼类生长催乳素的Ｎ－末端序列比较，具有较高的同源性；由此进一步证实，分离纯化得到的鲈鱼生长催乳素是正确的。

── Somatolactin (SL), a newly discovered protein pituitary hormone belonging to the GH/PRL fami- ly, was first isolated from Japanese sea bass (Lateolabrax japonicus) pituitary in this study. The somatolactin of Japanese sea bass (sbSL) was extracted under alkaline condition from its pituitary glands, and subsequently purified by gel filtration on a Sephadex G-100 column and reversed-phase high performance chromatography (rpHPLC).Japanese sea bass somatolactin (sbSL) was confirmed by the specific reaction with the antibody against chum salmon somatolactin (sSL ) through western blotting. The sbSL was found to consist of two forms with molecular weights of 23. 2 ×103 and 28. 4 ×103 u in SDS-polyacrylamide gel electrophoresis (SDS- PAGE ), the later may contain a form of glycosylation. Sixteen N-terminal amino acid sequence of sbSL was determined by the dansyl method according to Edman. The sixteen amino acid sequences of sbSL show a high- er homology compared to those of known teleost somatolactins, which further revealed that the isolated and purified pituitary hormone was Japanese sea bass somatolactin.