Shaw C, McKay D M, Halton D W, Thim L, Buchanan K D
Comparative Neuroendocrinology Research Group, School of Biology, Queen's University of Belfast, Northern Ireland.
Regul Pept. 1992 Mar 5;38(1):23-31. doi: 10.1016/0167-0115(92)90069-7.
Using a radioimmunoassay system employing an antiserum which recognises the common C-terminal tripeptide (YIL) of neurotensin (NT) and neuromedin N (NN), immunoreactivity was identified in extracts of brain (65.8 pmol/g), small intestine (44.2 pmol/g) and rectum (13.2 pmol/g) of the European common frog (Rana temporaria). No immunoreactivity was detected in extracts of stomach and skin. Reverse-phase HPLC analysis of each tissue extract resolved a single immunoreactive peptide with identical retention time in each case. The immunoreactive peptide was isolated by reverse-phase HPLC from brain extracts and an N-terminal pyroglutamyl residue was successfully removed enzymatically. The molecular mass of des(pyroglutamyl) frog NT, determined by plasma desorption mass spectroscopy, was 1440 Da. The primary structure of this peptide was determined by gas-phase sequencing and the calculated molecular mass, 1440.7 Da, was in close agreement with that derived by mass spectroscopy. The full primary structure of frog NT was established as: QSHISKARRPYIL. When compared with bovine NT, frog NT exhibits five amino acid substitutions in the N-terminal region, whereas the C-terminal hexapeptide sequence (RRPYIL), which mediates the classical biological effects of NT, is completely conserved. Amphibia thus possess a tridecapeptide NT which is analogous to that of higher vertebrates and considerable constraints on the primary structure of the C-terminal biologically-active core have existed for a vast evolutionary time span.
使用一种放射免疫分析系统，该系统采用一种抗血清，这种抗血清能够识别神经降压素（NT）和神经介素N（NN）共同的C末端三肽（YIL），在欧洲普通青蛙（林蛙）的脑提取物（65.8 pmol/g）、小肠提取物（44.2 pmol/g）和直肠提取物（13.2 pmol/g）中检测到免疫反应性。在胃和皮肤提取物中未检测到免疫反应性。对每个组织提取物进行反相高效液相色谱分析，在每种情况下都解析出一个具有相同保留时间的单一免疫反应性肽。通过反相高效液相色谱从脑提取物中分离出免疫反应性肽，并通过酶法成功去除了N末端焦谷氨酰残基。通过等离子体解吸质谱法测定的去（焦谷氨酰）青蛙NT的分子量为1440 Da。该肽的一级结构通过气相测序确定，计算出的分子量为1440.7 Da，与质谱法得出的结果非常一致。青蛙NT的完整一级结构确定为：QSHISKARRPYIL。与牛NT相比，青蛙NT在N末端区域有五个氨基酸取代，而介导NT经典生物学效应的C末端六肽序列（RRPYIL）则完全保守。因此，两栖动物拥有一种十三肽NT，它与高等脊椎动物的NT类似，并且在漫长的进化时间跨度内，C末端生物活性核心的一级结构受到了相当大的限制。
