Membrane-bound enzymes and their role in processing of the dynorphins and of the proenkephalin octapeptide Met-enkephalin-Arg-Gly-Leu
Membrane-bound enzymes and their role in processing of the dynorphins and of the proenkephalin octapeptide Met-enkephalin-Arg-Gly-Leu
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膜结合酶及其在强啡肽和脑啡肽原八肽 Met-脑啡肽-Arg-Gly-Leu 加工中的作用
作者：
M. Benuck;M. Berg;N. Marks
突触体膜（SPM）结合的外肽酶和内肽酶在几个位点切割强啡肽和Met-脑啡肽-Arg-Gly-Leu以产生较短的片段;其中包括来自1-17的强啡肽1-8和来自Metenkephalin-Agr-Gly-Leu的Met-脑啡肽。最脆弱的位点是被膜结合氨肽酶切割的Tyr-Gly键，较短的肽比较长的肽降解得更快。纯化的对磷酰胺敏感的金属内肽酶使Gly 3-Phe 4键处的较短肽序列失活，并且还使Arg 7-Ile 8键处的1-13和1-17序列失活。纯化的金属内肽酶的kcat/Km比为亮脑啡肽和脑啡肽原八肽比强啡肽1-8、1-13和1-17高20-30倍。强啡肽1-13和1-17可作为广泛分布的CNS神经肽强啡肽1-8的前体，因为它们被对磷酰胺不敏感的单独SPM内肽酶切割。SPM单羧肽酶将强啡肽1-13转化为1-12（释放Lys），二肽羧肽酶将强啡肽1-8转化为1-6;脑啡肽八肽通过两种羧肽酶的顺序作用（释放Leu和Arg-Gly）作为Met-脑啡肽的前体。
Synaptosomal membrane (SPM) bound exo- and endopeptidases cleave the dynorphins and Met-enkephalin-Arg-Gly-Leu at several sites to produce shorter fragments; among these are dynorphin 1–8 from 1–17, and Met-enkephalin from Metenkephalin-Agr-Gly-Leu. the most vulnerable site is the Tyr-Gly bond cleaved by membrane-bound aminopeptidase(s), with the shorter peptides degraded more rapidly than the longer ones. A purified metalloendopeptidase sensitive to phosphoramidon inactivates the shorter peptide sequences at the Gly3-Phe4 bond, and the 1–13 and 1–17 sequences also at the Arg7-Ile8 bond. The kcat/Km ratios for purified metalloendopeptidase were 20–30 times higher for Leu-enkephalin and the proenkephalin octapeptide than for dynorphins 1–8, 1–13, and 1–17. Dynorphins 1–13 and 1–17 may serve as precursors for the widely distributed CNS neuropeptide dynorphin 1–8 since they were cleaved by a separate SPM endopeptidase insensitive to phosphoramidon. SPM monocarboxypeptidase converted dynorphin 1–13 to 1–12 (release of Lys) and dipeptidyl carboxypeptidase converted dynorphin 1–8 to 1–6; enkephalin octapeptide served as a precursor of Met-enkephalin by sequential action (release of Leu and Arg-Gly) of both carboxypeptidases.
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影响因子：
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作者：
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影响因子：
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作者：
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DOI：
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DOI：
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发表时间：
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期刊：
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影响因子：
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