Noe B D, Bauer G E, Steffes M W, Sutherland D E, Najarian J S
Horm Metab Res. 1975 Jul;7(4):314-22. doi: 10.1055/s-0028-1093721.
Viable pancreatic islets were isolated from the pancreas of humans using modifications of the collagenase digestion and Ficoll gradient techniques. Gel filtration of tissue extracts following islet incubation in the presence of 3H- tryptophan indicated that radioactivity becomes incorporated into at least two islet proteins. The larger of the two (LGI) has the approximate molecular size of proinsuiln and the smaller coelutes with glucagon as determined by column standardization. Radioimmunoassay of the gel filtration eluate for glucagon revealed that both molecules have glucagon immunoreactivity. Gel filtration in the presence of 8M urea did not alter the elution pattern of the LGI molecule. Polyacrylamide gel electrophoresis was performed on these glucagon immunoreactive molecules. The 3H radioactivity and the glucagon immunoreactivity of the smaller molecule were found to co-migrate electrophoretically with crystalline porcine glucagon and monodesamidoglucagon. With electrophoresis at high pH the electrophoretic mobility of the LGI molecule proved to be lower than that of glucagon. Partial tryptic degradation of the human LGI molecule yields 3H-tryptophan labeled products having charge and immunologic characteristics indistinguishable from porcine glucagon and monodesamidoglucagon. Although further investigation is indicatend may thus serve as a precursor or an intermediate in human glucagon biosynthesis.
采用胶原酶消化和菲可梯度技术的改良方法，从人类胰腺中分离出有活力的胰岛。在胰岛与3H-色氨酸一起孵育后，对组织提取物进行凝胶过滤，结果表明放射性至少掺入到两种胰岛蛋白中。通过柱标准化测定，两者中较大的一种（LGI）的分子大小与胰岛素原相近，较小的一种与胰高血糖素一同洗脱。对凝胶过滤洗脱液进行胰高血糖素放射免疫测定，结果显示这两种分子都具有胰高血糖素免疫反应性。在8M尿素存在下进行凝胶过滤，并未改变LGI分子的洗脱模式。对这些具有胰高血糖素免疫反应性的分子进行聚丙烯酰胺凝胶电泳。发现较小分子的3H放射性和胰高血糖素免疫反应性在电泳中与结晶猪胰高血糖素和单去酰胺基胰高血糖素共同迁移。在高pH值下进行电泳时，LGI分子的电泳迁移率被证明低于胰高血糖素。人LGI分子经部分胰蛋白酶降解后产生的3H-色氨酸标记产物，其电荷和免疫学特征与猪胰高血糖素和单去酰胺基胰高血糖素无法区分。尽管还需要进一步研究，但它可能因此在人胰高血糖素生物合成中作为前体或中间体。
