Proton affinity of diastereoisomers of modified prolines using the kinetic method and density functional theory calculations: role of the cis/trans substituent on the endo/exo ring conformation.
The proton affinity (PA) of cis/trans-3-prolinoleucines and cis/trans-3-prolinoglutamic acids have been studied by the kinetic method and density functional theory (DFT) calculations. Several conformations of the neutral and the protonated modified prolines, in particular the endo and exo ring conformations, were analyzed with respect to their contribution to the PA values. When the substituent is an alkyl, both the diastereoisomers have the same PA value. However, the PA values for the diastereoisomers are different when the substituted chain contains functional groups (e.g. a carboxyl group). This variation in PA values could be attributed to the existence of intramolecular hydrogen bonds.
Mezzache
S
S
Synthèse, Structure et Fonction de Molécules Bioactives, CNRS, UMR 7613, Université Pierre et Marie Curie, 4 place Jussieu, 75252 Paris cedex 05, France.
Pepe
C
C
Karoyan
P
P
Fournier
F
F
Tabet
J-C
JC
D000465:Algorithms; D018698:Glutamic Acid / Q000031:analogs & derivatives / Q000737:chemistry; D007700:Kinetics; D007930:Leucine / Q000031:analogs & derivatives / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D011392:Proline / Q000031:analogs & derivatives* / Q000737:chemistry*; D013237:Stereoisomerism; D013816:Thermodynamics
D018698:Glutamic Acid; D011392:Proline; D007930:Leucine