Udenfriend S, Kilpatrick D L
Arch Biochem Biophys. 1983 Mar;221(2):309-23. doi: 10.1016/0003-9861(83)90149-2.
The enkephalins are present in many tissues not only as the free pentapeptides, but also as internal sequences in larger polypeptides of varying size. Fourteen enkephalin-containing peptides (EC peptides) from beef adrenal medulla were isolated and sequenced, and the presence of a protein that contained several [Met]enkephalin sequences and one of [Leu]enkephalin was demonstrated. Because the latter was assumed to represent the gene product, it was named proenkephalin. Sequence data from the EC peptides made possible the synthesis of a polynucleotide probe with essentially no degeneracy and permitted the cloning of a partial proenkephalin cDNA. The complete structure of proenkephalin was deduced from both peptide and cDNA sequencing data. Proenkephalin is now known to be one of three enkephalin-containing gene products, each of which gives rise to many physiologically active peptides.
脑啡肽不仅以游离五肽的形式存在于许多组织中，还作为不同大小的较大多肽中的内部序列存在。从牛肾上腺髓质中分离并测序了14种含脑啡肽的肽（EC肽），并证明存在一种含有多个[甲硫氨酸]脑啡肽序列和一个[亮氨酸]脑啡肽序列的蛋白质。由于后者被认为代表基因产物，因此将其命名为前脑啡肽。来自EC肽的序列数据使得合成基本上没有简并性的多核苷酸探针成为可能，并允许克隆部分前脑啡肽cDNA。前脑啡肽的完整结构是从肽和cDNA测序数据推导出来的。现在已知前脑啡肽是三种含脑啡肽的基因产物之一，每种基因产物都能产生许多生理活性肽。
