A Novel Mechanism of Proton Transfer in Protonated Peptides

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• 作者：Petr Kulhá ; nek ; Edward W. Schlag ; and Jaroslav Ko//pubs.acs.org/images/entities/ccaron.gif" border="0">a
• 刊名：Journal of the American Chemical Society
• 出版年：2003
• 出版时间：November 12, 2003
• 年：2003
• 卷：125
• 期：45
• 页码：13678 - 13679
• 全文大小：39K
• 年卷期：v.125,no.45(November 12, 2003)
• ISSN：1520-5126

文摘

The study presents quantum-chemical calculations on proton transfer in protonated N-acetylglycyl-N¹-methylglycinamide (AGA) as a short oligopeptide model. All calculations employ the B3LYP functional and the 6-31++G** basis set. Two different mechanisms of proton transfer are discussed. The rate-determining step of the first mechanism exhibits an energy barrier of about 17.7 kcal mol^-1, and it is represented by an isomerization of the proton around the double bond of the carbonyl group. The second mechanism is based on the large conformational flexibility of AGA, where all carbonyl oxygens cooperate. The rate-determining step of this mechanism exhibits an energy barrier of only 8.3 kcal mol^-1.