Molecular recognition of vasoactive peptides : basis for Physiological action

用圆二色谱、核磁共振波谱、距离几何、分子动力学和能量最小化方法研究了垂体腺苷激活多肽(PACAP)及其相关多肽(PRP)的结构。PACAP38和27最初具有无序的N-末端结构，然后是螺旋结构。PRP在3-20之间为螺旋结构。在此基础上，利用固相法合成了几种PACAP相关多肽。PACAP是一种有效的血管扩张剂。PACAP37、36、35、34和33的血管效应峰值与PACAP38相似，但作用持续时间取决于多肽的长度。PACAP对豚鼠胆囊的作用与VIP相反。PACAP和VIP的C末端是两个序列差异最大的多肽，对它们的识别并不重要，但N末端的柔性部分负责它们对胆囊壁的相反作用。用放射免疫法研究了PACAP38、PACAP27和PRP在豚鼠体内的组织分布。大量的PACAP/PRP不仅存在于中枢神经系统，而且存在于胃肠道，它们存在于肠神经元中。用化学方法合成了内皮素和分泌素受体的几个片段，并提出了它们的特异性抗体。胰液分泌素受体片段抗血清经SDS-聚丙烯酰胺凝胶电泳法免疫印迹，在50 kDa左右出现阳性条带。大鼠胰管染色较深，腺泡较少。

The structure of pituitary adenylate activating polypeptide (PACAP) and (PACAP) related peptide (PRP) were investigated by CD and NMR spectroscopy, distance geometry, molecular dynamics and energy minimization calculations. PACAP38 and 27 had an initial disordered N-terminal structure, followed by a helical structures. PRP had a helical structure from 3-20th. Based on these results, several PACAP related peptides were synthesized by a solid phase peptide synthesizer. PACAP was a potent vosodilator. Vascular effects of PACAP was independent of the endothelium and was not blocked by NO synthase inhibitors.PACAP37,36,35,34, and 33 had similar peak vascular effects to PACAP38 but the duration of action was dependent on the length of the peptide. PACAP had an opposite effect to VIP on the guinea pig gallbladder. The C-terminus of PACAP and VIP,where two peptides show the largest difference in sequence, was not important for the recognition of them but the N-terminal flexible portion was responsible for their opposite actions on the gallbladder. Tissue distribution of PACAP38, PACAP27, and PRP in guinea pigs was investigated by radioimmunoassay. Significant amounts of PACAP/PRP were present not only in the central nervous system but also in the gastrointestinal tract, where they were present in the enteric neurons. Several fragments of endothelin and secretin receptors were chemically synthesized and their specific antibodies were raised. On immunoblotts of pancreatic membranes subjected to SDS-polyacrylamide gel electrophoresis, antisera against secretin receptor fragments showed positive bands around 50kDa. Rat pancreatic ducts were strongly stained and acini with less degree by these antisera.