Bechinger B
Max Planck Institute for Biochemistry, 82152 Martinsried, Germany.
Biophys J. 2001 Oct;81(4):2251-6. doi: 10.1016/S0006-3495(01)75872-9.
Polyalanine-based peptides were prepared by solid-phase peptide synthesis, labeled with (15)N at selected sites, reconstituted into oriented phosphatidylcholine bilayers, and investigated by proton-decoupled (15)N solid-state NMR spectroscopy. The anisotropic (15)N chemical shift is a direct indicator of helix alignment with respect to the membrane normal. The in-plane to transmembrane equilibrium is the focus of this study. Time- and solvent-dependent transmembrane alignments of K(3)A(18)K(3) have been obtained, and these are stabilized when a few alanine residues are replaced with leucine. The results are discussed in the context of a model where polyalanines adopt a variety of configurations, which are interconnected by multiple equilibria. The data indicate hydrophobicity values of alanine close to zero when studied in the context of helical polypeptides (> or =24 residues) and phospholipid bilayers.
基于聚丙氨酸的肽通过固相肽合成制备，在选定位置用（15）N标记，重构成定向磷脂酰胆碱双层膜，并通过质子去耦（15）N固态核磁共振光谱进行研究。各向异性（15）N化学位移是螺旋相对于膜法线排列的直接指标。面内到跨膜的平衡是本研究的重点。已获得K（3）A（18）K（3）随时间和溶剂变化的跨膜排列，当几个丙氨酸残基被亮氨酸取代时，这些排列会稳定下来。在一个模型的背景下讨论了结果，该模型中聚丙氨酸采用多种构型，这些构型通过多个平衡相互连接。数据表明，在螺旋多肽（≥24个残基）和磷脂双层膜的背景下研究时，丙氨酸的疏水性值接近零。
