Intrinsic Conformational Characteristics of ,-Diphenylglycine

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• 作者：Jordi Casanovas ; David Zanuy ; Ruth Nussinov ; Carlos Alem&aacute ; n
• 刊名：Journal of Organic Chemistry
• 出版年：2007
• 出版时间：March 16, 2007
• 年：2007
• 卷：72
• 期：6
• 页码：2174 - 2181
• 全文大小：280K
• 年卷期：v.72,no.6(March 16, 2007)
• ISSN：1520-6904

文摘

Quantum mechanical calculations at the B3LYP/6-31+G(d,p) level have been used to investigate theintrinsic conformational preferences of ,-diphenylglycine, a simple ,-dialkylated amino acid bearingtwo phenyl substituents on the -carbon, in both the gas phase and aqueous solution. Nine minimumenergy conformations have been characterized for the N-acetyl-N'-methylamide derivative within a relativeenergy range of about 9 kcal/mol. The relative stability of these structures is largely influenced by specificbackbone···side chain and side chain···side chain interactions that can be attractive (N-H··· and C-H···) or repulsive (C=O···). On the other hand, comparison with the minimum energy conformationscalculated for -aminoisobutyric acid, in which the two phenyl substituents are replaced by methyl groups,revealed that the bulky aromatic rings of ,-diphenylglycine induce strain in the internal geometry ofthe peptide. Finally, a set of force-field parameters for classical Molecular Mechanics calculations wasdeveloped for the investigated amino acid. Molecular Dynamics simulations in aqueous solutions havebeen carried out to validate the parameters obtained.