Li S C, Deber C M
Nat Struct Biol. 1994 Aug;1(8):558. doi: 10.1038/nsb0894-558.
The frequent occurrence of beta-sheet promoting residues such as Ile, Val, and Thr in the alpha-helical transmembrane segments of most integral membrane proteins suggests that the helical propensities of these residues are altered in the hydrophobic environment of the lipid bilayer. Systematic studies of model peptides by circular dichroism spectroscopy in various micellar/vesicular media allow the establishment of a ranking order of helical propensity for uncharged amino acids in the membrane environment. In contrast to their conformational preferences in water, the helical proclivity of amino acids in membranes is shown to be governed by their side chain hydrophobicity, and by the hydropathy of the local peptide segments in which the residues reside.
大多数整合膜蛋白的α-螺旋跨膜区段中频繁出现异亮氨酸、缬氨酸和苏氨酸等促进β-折叠的残基，这表明这些残基的螺旋倾向在脂质双层的疏水环境中发生了改变。通过圆二色光谱法在各种胶束/囊泡介质中对模型肽进行系统研究，能够确定膜环境中不带电荷氨基酸的螺旋倾向排序。与它们在水中的构象偏好相反，膜中氨基酸的螺旋倾向显示受其侧链疏水性以及残基所在局部肽段的亲水性支配。
