Publication details

Influence of stereochemistry on proton transfer in protonated tripeptide models

Authors

SOLIMAN Namat Ali KULHÁNEK Petr KOČA Jaroslav

Year of publication 2012
Type Article in Periodical
Magazine / Source Journal of Molecular Modeling
MU Faculty or unit

Central European Institute of Technology

Citation
Web http://link.springer.com/article/10.1007%2Fs00894-011-1116-2
Doi http://dx.doi.org/10.1007/s00894-011-1116-2
Field Biochemistry
Keywords Conformational rearrangement; Density functional theory; Protonated peptides; Proton transfer
Description Vectorial proton transfer among carbonyl oxygen atoms was studied in two models of tripeptide via quantum chemical calculations using the hybrid B3LYP functional and the 6-31++G** basis set. Two principal proton transfer pathways were found: a first path involving isomerization of the proton around the double bond of the carbonyl group, and a second based on the large conformational flexibility of the tripeptide model where all carbonyl oxygen atoms cooperate. The latter pathway has a rate-determining step energy barrier that is only around half of that for the first pathway. As conformational flexibility plays a crucial role in second pathway, the effect of attaching methyl groups to the alpha carbon atoms was studied. The results obtained are presented for all four possible stereochemical configurations.
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