Metorphamide: isolation, structure, and biologic activity of an amidated opioid octapeptide from bovine brain.
Metorphamide: isolation, structure, and biologic activity of an amidated opioid octapeptide from bovine brain.
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DOI：
10.1073/pnas.80.23.7362
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发表时间：
1983-12
影响因子：
11.1
通讯作者：
Eckard Weber;F. Esch;Peter Bőhlen;S. Paterson;A. Corbett;A. Mcknight;H. Kosterlitz;Jack D. Barchas;Christopher H. Evans
中科院分区：
文献类型：
--
作者：
Eckard Weber;F. Esch;Peter Bőhlen;S. Paterson;A. Corbett;A. Mcknight;H. Kosterlitz;Jack D. Barchas;Christopher H. Evans
从牛脑尾状核中提取的酸性丙酮提取物中含有一个酰胺化阿片八肽，其结构如下：Tyr-Gly-Gly-Phe-Met-Arg-Arg-Val-NH2。这种多肽已被命名为甲氧法胺。牛甲氨蝶胺似乎是由脑啡肽原蛋白分解而来的，前脑啡肽是脑啡肽和亮氨酸脑啡肽的共同前体。前体内的裂解导致甲氨蝶胺的羧基末端发生在单个精氨酸残基上，紧随其后的是羧基末端的甘氨酸转化为酰胺基。采用放射免疫法检测牛尾状核提取液中甲氨蝶胺的含量，并通过凝胶过滤和反相高效液相色谱分离纯化甲氨蝶胺。氨基酸组成分析和气相测序仪中的自动埃德曼降解证实了假定的氨基酸序列。牛甲氨酰胺的羧基末端酰胺化反应表现为对羧肽酶A消化的稳定性和放射免疫分析中的完全交叉反应，该反应需要羧基末端酰胺作为识别位点的一部分。一种合成的甲氨蝶胺复制品以及几个合成的类似物在几个生物测定和结合试验中被测试阿片类药物的活性，发现甲氨蝶胺具有很高的u结合活性。甲氨蝶胺是已知的唯一一种天然存在的阿片肽，具有较高的u结合活性。Kappa结合活性约等于u结合活性的50%，但增量结合活性可忽略不计。
Acid acetone extracts of caudate nucleus from bovine brain were found to contain an amidated opioid octapeptide with the following structure: Tyr-Gly-Gly-Phe-Met-Arg-Arg-Val-NH2. The peptide has been named metorphamide. Bovine metorphamide appears to be derived by proteolytic cleavage from proenkephalin, the common precursor to [Met5]enkephalin and [Leu5]enkephalin. The cleavage within the precursor giving rise to the carboxyl terminus of metorphamide occurs at a single arginine residue and is followed by transformation of a carboxyl-terminal glycine into an amide group. Metorphamide was detected in bovine caudate nucleus extracts by radioimmunoassay, and it was purified to homogeneity by gel filtration and reversed-phase high performance liquid chromatography. Amino acid composition analysis and automated Edman degradation in the gas-phase sequencer confirmed the postulated amino acid sequence. Carboxyl-terminal amidation of bovine metorphamide was shown by stability to carboxypeptidase A digestion and full crossreactivity in a radioimmunoassay that required the carboxyl-terminal amide as part of the recognition site. A synthetic replicate of metorphamide as well as several synthetic analogs were tested for opioid activity in several bioassays and binding assays, and metorphamide was found to have a high mu-binding activity. Metorphamide is the only known naturally occurring opioid peptide that has a high mu-binding activity. The kappa-binding activity is approximately equal to 50% that of the mu-binding activity, but delta-binding activity is negligible.