CONFORMATION OF GRAMICIDIN-A
CONFORMATION OF GRAMICIDIN-A
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DOI：
10.1021/bi00723a001
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发表时间：
1974-01-01
期刊：
影响因子：
2.9
通讯作者：
BLOUT, ER
中科院分区：
文献类型：
--
作者：
VEATCH, WR;FOSSEL, ET;BLOUT, ER
William R. Veatch, Eric T. Fossel, and Elkan R. Blout*摘要：Gramicidin A被认为可以形成一个二聚体通道，碱离子和氢离子可以通过该通道通过脂质双分子层膜。本文描述了从单一有机溶剂体系中分离出来的四种构象，并分别用圆二色性、质子核磁共振和红外光谱进行了表征。Three distinct （jlramicidin A）是一种线性多肽，其序列如下（Sarges and Witkop, 1965）：甲酰基- l-缬氨酸-甘氨酸- l- ala - d - leu - l- ala - d -缬氨酸- l-缬氨酸- d -缬氨酸-(L-Trp-D-Leu) 3- l- trp -乙醇酰胺。如果甘氨酸被认为是一个潜在的D残基，那么这个序列是一个严格的交替序列；所有侧链都是相对疏水的。Gramicidin A促进碱离子和氢离子通过天然（Harold and Baarda, 1967; Chappell and Crofts, 1965; Harris and Press-man, 1967）和人工脂质双分子层膜（Mueller and Rudin, 1967; Myers and Haydon, 1972）的被动扩散。有强有力的证据表明，gramicidin A形成了一个跨越膜烃的通道（Hladky和Haydon, 1972； Krasne等，1971），一些证据表明，该通道需要两个gramicidin A分子（tosteeson等，1968；Bamberg和Láuger， 1973）。为了寻找证据来批判性地评估参与跨膜通道的gramicidin A的构象模型，几组工作人员（Glickson等人，1972；Urry等人，1972；Isbell等人，1972；Rothschild和Stanley， 1974）研究了溶液中gramicidin的构象和聚集。尽管非极性有机溶剂可能是膜内部的良好模型环境，但必须记住，脂质双分子层膜本质上是极性和非极性区域的异质结合。
William R. Veatch, 1 Eric T. Fossel, and Elkan R. Blout* abstract: Gramicidin A is thought to form a dimer channel through which alkali cations and hydrogen ions can pas-sively permeate lipid bilayer membranes. The present work describes four conformational species which have been iso-lated from a single organic solvent system and individually characterized by circular dichroism, proton nuclear mag-netic resonance, and infrared spectroscopy. Three distinct (jlramicidin A is a linear polypeptide with the following sequence (Sarges and Witkop, 1965): formyl-L-Val-Gly-L-Ala-D-Leu-L-Ala-D-Val-L-Val-D-Val-(L-Trp-D-Leu) 3-L-Trp-ethanolamide. If glycine is thought of as a potential D residue, then the sequence is a strictly alternatingldld; all side chains are relatively hydrophobic. Gramicidin A facilitates the passive diffusion of the alka-li cations and hydrogen ion through natural (Harold and Baarda, 1967; Chappell and Crofts, 1965; Harris and Press-man, 1967) and artificial lipid bilayer membranes (Mueller and Rudin, 1967; Myers and Haydon, 1972). There is strong evidence that gramicidin A forms a channel span-ning the membrane hydrocarbon (Hladky and Haydon, 1972; Krasne et al., 1971), and some evidence that the channel requires two molecules of gramicidin A (Tosteson et al., 1968; Bamberg and Láuger, 1973). In search of evidence to critically assess models for the conformation of the gramicidin A involved in thetrans-membrane channel, several groups of workers (Glickson et al., 1972; Urry et al., 1972; Isbell et al., 1972; Rothschild and Stanley, 1974) have examined the conformation and aggregation of gramicidin in solution. Although a nonpolar organic solvent may be a good model environment for the membrane interior, it must be borne in mind that a lipid bilayer membrane is essentially a heterogeneous apposition of polar and nonpolar regions.