Effect of side chain-backbone electrostatic interactions on the stability of alpha-helices.
Effect of side chain-backbone electrostatic interactions on the stability of alpha-helices.
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DOI：
10.1073/pnas.82.17.5585
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发表时间：
1985-09
影响因子：
11.1
通讯作者：
H. Scheraga
中科院分区：
文献类型：
--
作者：
H. Scheraga
核糖核酸酶A的C-肽α-螺旋的观察到的稳定性和从齐姆-布拉格参数σ和s（通过主客体技术获得）计算的稳定性之间的明显差异得到解决。侧链-主链离子-偶极相互作用在这两个系统中起作用。然而，它们在用于测定带电荷残基（如谷氨酸）的σ和s的无规共聚物中被平均化，但在特定序列共聚物（即C肽）中不被平均化，在特定序列共聚物中它们显著地有助于螺旋稳定性。在考虑特定序列的α-螺旋时，其内在的稳定自由能（以σ和s表示）必须通过位置依赖的稳定远程静电相互作用来增强。
An apparent discrepancy between the observed stability of the C-peptide alpha-helix of ribonuclease A and that computed from the Zimm-Bragg parameters sigma and s (obtained by the host-guest technique) is resolved. Side chain-backbone ion-dipole interactions play a role in both systems. However, they are averaged out in the random copolymers used to determine sigma and s for charged residues such as glutamic acid but not in the specific-sequence copolymer, namely, the C-peptide, where they contribute significantly to the helix stability. In considering a specific-sequence alpha-helix, its intrinsic stabilizing free energy (expressed in terms of sigma and s) must be augmented by position-dependent stabilizing long-range electrostatic interactions.