Jelokhani-Niaraki M, Nakashima K, Kodama H, Kondo M
Department of Chemistry, Faculty of Science and Engineering, Saga University, Saga 840-8502, Japan.
J Biochem. 1998 May;123(5):790-7. doi: 10.1093/oxfordjournals.jbchem.a022006.
The interaction and orientation of a membrane protein ion channel model, an alpha-aminoisobutyric acid analogue of gramicidin B (GBA), in egg yolk phosphatidylcholine vesicles was studied by means of fluorescence spectroscopic techniques. GBA helices form stable ion-conducting pores in membranes [Jelokhani-Niaraki et al. (1995) J. Chem. Soc. Perkin Trans. 2, 801-808]. In an alpha-helical model for the peptide, all Trp residues (intrinsic fluorophores) are distributed near the C-terminus. Fluorescence quenching experiments revealed the exposure of the helical peptides' C-termini to aqueous environments. Dansyl-labeled vesicles were used to investigate the GBA dynamism of the interaction with membranes. It was shown that considerable amounts of peptide reside on and in the vicinity of the outer surface of lipid bilayers. The transmembrane transfer to the inner layer is slow due to the high affinity of Trp residues for bilayer interfaces which anchor the peptide to the outer surface. A structural-functional interpretation of the GBA interaction with membranes is presented.
通过荧光光谱技术研究了膜蛋白离子通道模型——短杆菌肽B（GBA）的α-氨基异丁酸类似物在蛋黄磷脂酰胆碱囊泡中的相互作用和取向。GBA螺旋在膜中形成稳定的离子传导孔[杰洛哈尼-尼亚拉基等人（1995年）《化学学会会刊：珀金 Transactions 2》，801 - 808页]。在该肽的α-螺旋模型中，所有色氨酸残基（内在荧光团）分布在C末端附近。荧光猝灭实验揭示了螺旋肽的C末端暴露于水性环境。用丹磺酰标记的囊泡来研究GBA与膜相互作用的动态变化。结果表明，相当数量的肽存在于脂质双层外表面及其附近。由于色氨酸残基对双层界面具有高亲和力，从而将肽锚定在外表面，所以跨膜转移到内层的过程较慢。本文给出了GBA与膜相互作用的结构-功能解释。
