Bouchoux G, Salpin J-Y
Laboratoire des Mécanismes Réactionnels, UMR CNRS 7651, Ecole Polytechnique, 91128 Palaiseau Cedex, France.
Eur J Mass Spectrom (Chichester). 2003;9(4):391-402. doi: 10.1255/ejms.568.
The thermokinetic method is applied to a set of six amino acids (glycine, alanine, proline, serine, lysine, histidine) and 30 of their di- and tri-peptides for which experimental proton transfer rate constants were available. The comparison between the presently determined gas-phase basicities, GBs, of the amino acids with values obtained from equilibrium constant determination is generally good (a mean deviation of appoximately 3 kJ mol(-1) is observed). Derived proton affinities values are discussed. The gas-phase basicities of peptides provided by the present study correct several previously estimated values thus offering a more firm basis for structural discussion. Composite reaction efficiency curves indicate the existence, for several peptides, of at least two non-interconverting populations of protonated forms.
热动力学方法应用于一组六种氨基酸（甘氨酸、丙氨酸、脯氨酸、丝氨酸、赖氨酸、组氨酸）及其30种二肽和三肽，这些肽有可用的实验质子转移速率常数。目前测定的氨基酸气相碱度（GBs）与通过平衡常数测定获得的值之间的比较总体良好（观察到平均偏差约为3 kJ mol⁻¹）。讨论了推导的质子亲合势值。本研究提供的肽的气相碱度修正了几个先前估计的值，从而为结构讨论提供了更坚实的基础。复合反应效率曲线表明，对于几种肽，至少存在两个非相互转化的质子化形式群体。
