Krimm S, Abe Y
Proc Natl Acad Sci U S A. 1972 Oct;69(10):2788-92. doi: 10.1073/pnas.69.10.2788.
Previous perturbation treatments of the Amide I vibrations of beta polypeptides are inconsistent with a detailed normal coordinate analysis of crystalline polyglycine I. This analysis indicates that the D(10) interaction constant is essentially zero, rather than the large value (about 20 cm(-1)) required by the earlier application of the perturbation theory. It is suggested that the previously neglected D(11) term should be included in the perturbation expression, and it is shown that the physical origin of such a term can be accounted for by transition dipole coupling. This mechanism is shown to give a reasonable explanation of splittings of the C=O stretching vibrations in hydrogenbonded carboxylic acid dimers. Its application to beta polypeptides provides a satisfactory interpretation of splittings in the Amide I modes.
先前对β多肽酰胺I振动的微扰处理与结晶聚甘氨酸I的详细简正坐标分析不一致。该分析表明，D(10)相互作用常数基本为零，而不是早期微扰理论应用所要求的较大值（约20 cm⁻¹）。有人建议，微扰表达式中应包含先前被忽略的D(11)项，并且表明该项的物理起源可以用跃迁偶极耦合来解释。这种机制被证明可以合理解释氢键合羧酸二聚体中C=O伸缩振动的分裂。将其应用于β多肽可以对酰胺I模式中的分裂给出令人满意的解释。
