A Novel Mechanism of Proton Transfer in Protonated Peptides

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Authors	KULHÁNEK Petr SCHLAG Edward W. KOČA Jaroslav
Year of publication	2003
Type	Article in Periodical
Magazine / Source	Journal of the American Chemical Society
MU Faculty or unit	Faculty of Science
Citation
Web	http://dx.doi.org/10.1021/ja035800z
Field	Physical chemistry and theoretical chemistry
Keywords	proton transfer; proton exchange; proton interaction; DFT
Description	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, 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.
Related projects:	Biomolecular Center