Carraway R E, Mitra S P, Ferris C F
Endocrinology. 1986 Oct;119(4):1519-26. doi: 10.1210/endo-119-4-1519.
Treatment of mammalian plasmas or sera with pepsin gave rise to extraordinary quantities (1-5 microM) of immunoreactive neurotensin (NT)-related peptide(s). Although immunochemical and chromatographic analyses indicated that the peptides liberated by pepsin differed from authentic neurotensin, one of the major immunoreactive products displayed NT-like biological properties. Partially purified preparations of the immunoreactive peptides increased cutaneous vascular permeability when injected intradermally in rats and released histamine from isolated rat mast cells. The pepsin-generated peptides appeared to share the biologically active C-terminal portion of NT, since they reacted with antisera selective for this region but were not recognized by N-terminal-directed antisera. Gel permeation chromatography demonstrated the presence of two substrates in plasma which liberated iNT upon treatment with pepsin, one in the albumin fraction (mol wt, 65 K) and the other a globulin (mol wt, 350 K). A variety of other proteases and substrates failed to have this effect. These results suggest the existence of a system(s) in blood, analogous to the renin-angiotensin system, for the generation of biologically active NT-related peptides.
用胃蛋白酶处理哺乳动物血浆或血清会产生大量（1 - 5微摩尔）与免疫反应性神经降压素（NT）相关的肽。尽管免疫化学和色谱分析表明胃蛋白酶释放的肽与天然神经降压素不同，但主要的免疫反应性产物之一具有类似NT的生物学特性。当将免疫反应性肽的部分纯化制剂皮内注射到大鼠体内时，会增加皮肤血管通透性，并从分离的大鼠肥大细胞中释放组胺。胃蛋白酶产生的肽似乎共享NT具有生物活性的C末端部分，因为它们能与针对该区域的抗血清发生反应，但不被N末端导向的抗血清识别。凝胶渗透色谱法表明血浆中存在两种底物，在用胃蛋白酶处理后会释放出免疫反应性NT，一种在白蛋白部分（分子量65K），另一种是球蛋白（分子量350K）。多种其他蛋白酶和底物没有这种作用。这些结果表明血液中存在一个类似于肾素 - 血管紧张素系统的系统，用于产生具有生物活性的NT相关肽。
