Department of Chemistry, University of Puerto Rico at Mayagüez, Mayagüez, Puerto Rico 00681.
J Phys Chem A. 2012 Feb 2;116(4):1283-8. doi: 10.1021/jp210208m. Epub 2012 Jan 20.
We report gas-phase electronic structure calculations on helical peptides that act as scaffolds for imidazole-based hydrogen-bonding networks (proton wires). We have modeled various 21-residue polyalanine peptides substituted at regular intervals with histidines (imidazole-bearing amino acids), using a hybrid approach with a semiempirical method (AM1) for peptide scaffolds and density functional theory (B3LYP) for proton wires. We have computed energy landscapes including barriers for Grotthuss-shuttling-type proton motions though wires supported on 3(10)-, α- and π-helical structures, showing the 3(10)- and α-helices to be attractive targets in terms of high proton affinities, low Grotthuss shuttling barriers, and high stabilities. Moreover, bias forces provided by the helical dipole moments were found to promote unidirectional proton translocation.
我们报告了螺旋肽的气相电子结构计算，这些螺旋肽可以作为基于咪唑的氢键网络（质子导线）的支架。我们使用半经验方法（AM1）对肽支架和密度泛函理论（B3LYP）对质子导线的混合方法，对各种 21 个残基的聚丙氨酸肽进行了建模，这些肽每隔一定距离用组氨酸（带咪唑的氨基酸）取代。我们计算了包括质子通过支持在 3(10)-、α-和π-螺旋结构上的导线的 Grotthuss 穿梭型质子运动的势垒在内的能量景观，表明 3(10)-和α-螺旋在高质子亲和力、低 Grotthuss 穿梭势垒和高稳定性方面是有吸引力的目标。此外，螺旋偶极矩提供的偏置力被发现可以促进质子的单向转运。
