Lorenz R G, Tyler A N, Faull K F, Makk G, Barchas J D, Evans C J
Peptides. 1986 Jan-Feb;7(1):119-26. doi: 10.1016/0196-9781(86)90071-9.
Opioid-like immunoreactive material was extracted from the pituitary and brain of the Spiny Dogfish Shark Squalus acanthias. The immunoreactive material in the pituitary extracts was purified to apparent homogeneity by reverse phase high performance liquid chromatography and subsequently characterized by amino acid analysis, Edman degradation and fast atom bombardment mass spectrometry. The largest opioid-like peptide isolated contained 30 amino acids and showed 80 percent homology with salmon endorphin-II but less than 50 percent homology with human beta-endorphin. Three structural variants of this molecule were also characterized. These variants were shown to be shorter N-terminal fragments, two of which corresponded to cleavage products at the single basic residues arginine and lysine. Cleavage at a single lysine residue has not been reported for posttranslational processing of beta-endorphin in mammals and could represent a modification seen only in lower vertebrates. The remaining fragment corresponded to a loss of 3 residues from the C-terminus of the parent molecule. No alpha-N-acetylated peptides were detected. These results provide the first unequivocal confirmation of beta-endorphin in an elasmobranch and provide evidence of novel N-terminal variants of beta-endorphin.
从棘鲨（Squalus acanthias）的垂体和大脑中提取了类阿片免疫反应性物质。垂体提取物中的免疫反应性物质通过反相高效液相色谱法纯化至表观均一，随后通过氨基酸分析、埃德曼降解和快原子轰击质谱进行表征。分离出的最大类阿片肽含有30个氨基酸，与鲑鱼内啡肽-II有80%的同源性，但与人类β-内啡肽的同源性小于50%。该分子的三种结构变体也得到了表征。这些变体显示为较短的N端片段，其中两个对应于在单个碱性残基精氨酸和赖氨酸处的切割产物。在哺乳动物中，β-内啡肽的翻译后加工尚未报道在单个赖氨酸残基处的切割，这可能代表仅在低等脊椎动物中出现的一种修饰。其余片段对应于母体分子C端缺失3个残基。未检测到α-N-乙酰化肽。这些结果首次明确证实了板鳃亚纲动物中存在β-内啡肽，并提供了β-内啡肽新型N端变体的证据。
