Mezzache S, Pepe C, Karoyan P, Fournier F, Tabet J-C
Synthèse, Structure et Fonction de Molécules Bioactives, CNRS, UMR 7613, Université Pierre et Marie Curie, 4 place Jussieu, 75252 Paris cedex 05, France.
Rapid Commun Mass Spectrom. 2005;19(16):2279-83. doi: 10.1002/rcm.2049.
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.
通过动力学方法和密度泛函理论（DFT）计算研究了顺式/反式-3-脯氨酰亮氨酸和顺式/反式-3-脯氨酰谷氨酸的质子亲和力（PA）。分析了中性和质子化修饰脯氨酸的几种构象，特别是内型和外型环构象对PA值的贡献。当取代基为烷基时，两种非对映异构体具有相同的PA值。然而，当取代链含有官能团（如羧基）时，非对映异构体的PA值不同。PA值的这种变化可归因于分子内氢键的存在。
