Precise structural analysis of α-helical polypeptide by quantum-chemical calculation related to reciprocal side-chain combination of two L-phenylalanine residues

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• 作者：Subaru Niimura ; Hiromichi Kurosu ; Akira Shoji
• 关键词：Quantum-chemical calculation ; L-phenylalanine ; Reciprocal side-chain combination ; α ; -Helix ; Chemical shift
• 刊名：Journal of Molecular Structure
• 出版年：2010
• 出版时间：30 April 2010
• 年：2010
• 卷：970
• 期：1-3
• 页码：96-100
• 全文大小：237 K

文摘

To clarify the positive role of side-chain conformation in the stability of protein secondary structure (main-chain conformation), we successfully calculated the optimization structure of a series of well-defined α-helical octadecapeptides composed of two L-phenylalanine (Phe) and 16 L-alanine (Ala) residues, based on the molecular orbital calculation with density functional theory (DFT/B3LYP/6-31G(d)). From the total energy calculation and the precise secondary structural analysis, we found that the conformational stability of the α-helix is closely related to the reciprocal side-chain combinations (such as positional relation and side-chain conformation) of two Phe residues in this system. Furthermore, we demonstrated that the ¹H, ¹³C, ¹⁵N and ¹⁷O isotropic chemical shifts of each Phe residue depend on the respective side-chain conformations of the Phe residue.