Milon A, Miyazawa T, Higashijima T
Department of Biophysics and Biochemistry, Faculty of Science, University of Tokyo, Japan.
Biochemistry. 1990 Jan 9;29(1):65-75. doi: 10.1021/bi00453a009.
Leu-enkephalin, [D-Ala2]Leu-enkephalin, and [D-Ala2]Leu-enkephalinamide (agonists) and [L-Ala2]Leu-enkephalin (inactive analogue) bind to lipid bilayer consisting of phosphatidylcholine and phosphatidylserine. The conformations that these compounds assume, once bound to perdeuterated phospholipid bilayer, have been shown to be unique, as shown by the transferred nuclear Overhauser effect (TRNOE) of 1H NMR spectroscopy. In addition, their location in the bilayer was analyzed by TRNOE in the presence of spin-labeled phospholipids. These analyses showed a clear relationship between the activity and the peptide-membrane interaction. The three active peptides, when bound to membranes, adopt the same conformation, characterized by a type II' beta-turn around Gly3-Phe4 and a gamma-turn around Gly2 (or D-Ala2). The inactive analogue, [L-Ala2]Leu-enkephalin, displayed a completely different TRNOE pattern corresponding to a different conformation in the membrane-bound state. The tyrosine residue of the active compounds is not inserted into the interior of membrane, but it is inserted into the bilayer for the L-Ala2 analogue. According to these results, [L-Ala2]Leu-enkephalin may be explained to be inactive because the mode of binding to the membranes is different from that of active compounds.
亮脑啡肽、[D - Ala2]亮脑啡肽和[D - Ala2]亮氨酸脑啡肽酰胺（激动剂）以及[L - Ala2]亮脑啡肽（无活性类似物）与由磷脂酰胆碱和磷脂酰丝氨酸组成的脂质双层结合。这些化合物一旦与全氘代磷脂双层结合所呈现的构象已被证明是独特的，这通过1H NMR光谱的转移核Overhauser效应（TRNOE）得以体现。此外，在存在自旋标记磷脂的情况下，通过TRNOE分析了它们在双层中的位置。这些分析表明活性与肽 - 膜相互作用之间存在明确的关系。这三种活性肽在与膜结合时采用相同的构象，其特征是围绕Gly3 - Phe4形成II'型β - 转角以及围绕Gly2（或D - Ala2）形成γ - 转角。无活性类似物[L - Ala2]亮脑啡肽在膜结合状态下呈现出完全不同的TRNOE模式，对应于不同的构象。活性化合物的酪氨酸残基并未插入膜内部，但对于L - Ala2类似物而言，它插入了双层中。根据这些结果，[L - Ala2]亮脑啡肽可能由于其与膜的结合方式不同于活性化合物而被解释为无活性。
