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.

Faculty of Science National Centre for Biomolecular Research Masaryk University Kamenice 5 CZ 625 00 Brno Czech Republic

See more in PubMed

J Bioenerg Biomembr. 2000 Oct;32(5):493-500 PubMed

Annu Rev Biophys Biophys Chem. 1990;19:7-41 PubMed

J Biol Inorg Chem. 2002 Mar;7(3):284-98 PubMed

J Am Chem Soc. 2001 Apr 4;123(13):3006-12 PubMed

Rapid Commun Mass Spectrom. 2001;15(8):651-63 PubMed

J Am Chem Soc. 2003 Nov 12;125(45):13678-9 PubMed

Curr Opin Chem Biol. 2001 Dec;5(6):626-33 PubMed

J Am Soc Mass Spectrom. 1990 Feb;1(1):53-65 PubMed

Mass Spectrom Rev. 1997 Mar-Apr;16(2):53-71 PubMed

Anal Chem. 1991 Dec 15;63(24):1193A-1203A PubMed

Phys Rev B Condens Matter. 1988 Jan 15;37(2):785-789 PubMed

Rapid Commun Mass Spectrom. 2008 Sep;22(18):2946-54 PubMed

Rapid Commun Mass Spectrom. 2001;15(8):637-50 PubMed

Biochemistry. 2002 Aug 6;41(31):9991-10001 PubMed

Rapid Commun Mass Spectrom. 2000;14(6):417-31 PubMed