Mechanism of cyclosporin A biosynthesis. Evidence for synthesis via a single linear undecapeptide precursor.
Mechanism of cyclosporin A biosynthesis. Evidence for synthesis via a single linear undecapeptide precursor.
复制标题
DOI：
10.1016/s0021-9258(17)42019-9
复制
发表时间：
1994-01
期刊：
影响因子：
--
通讯作者：
J. Dittmann;R. Wenger;H. Kleinkauf;Alfons Lawen
中科院分区：
文献类型：
--
作者：
J. Dittmann;R. Wenger;H. Kleinkauf;Alfons Lawen
环孢素A是由一种多酶多肽环孢素合成酶合成的。这种酶催化至少40个反应步骤的组装带状机制。它通过氨基丙烯酸活化环孢素A的所有组成氨基酸为硫酯，并进行特异性的n -甲基化反应。在延伸过程中，被激活的氨基酸通过肽键连接，形成酶结合的新生肽链。分离了生长环孢素A链的部分线状肽，测定了其n端氨基酸。环孢素A分子第8位的d -丙氨酸是环孢素A生物合成过程的起始氨基酸。环孢素A生长肽链的4个中间肽可以分离鉴定。它们都代表环孢素A以d -丙氨酸开头的部分序列。这些中间肽通过硫酯键与环孢素合成酶结合，可以用甲酸释放肽来证明。这些多肽强烈暗示了环孢素a的单一线性肽前体的逐步合成。
Cyclosporin A is synthesized by cyclosporin synthetase, a multienzyme polypeptide. This enzyme catalyzes at least 40 reaction steps in an assembly belt-like mechanism. It activates all constituent amino acids of cyclosporin A to thioesters via amino acyladenylates and carries out specific N-methylation reactions. During elongation, the activated amino acids are linked by peptide bonds leading to enzyme-bound nascent peptide chains. Some of the linear peptides of the growing cyclosporin A chain were isolated and their N-terminal amino acid was determined. D-Alanine at position 8 of the cyclosporin A molecule was found to be a starting amino acid in the biosynthetic process of cyclosporin A formation. Four intermediate peptides of the growing peptide chain of cyclosporin A could be isolated and identified. All of them represent partial sequences of cyclosporin A starting with D-alanine. That these intermediate peptides were bound by thioester linkage to cyclosporin synthetase could be demonstrated by liberation of the peptides with performic acid. The peptides strongly suggest the stepwise synthesis of a single linear peptide precursor of cyclosporin A.