Gas-phase basicity of glycine, alanine, proline, serine, lysine, histidine and some of their peptides by the thermokinetic method

Eur. J. Mass Spectrom. 9, 391–402 (2003)
DOI: 10.1255/ejms.568

Gas-phase basicity of glycine, alanine, proline, serine, lysine, histidine and some of their peptides by the thermokinetic method

G. Bouchoux^a and J-Y. Salpin^b
^aLaboratoire des Mécanismes Réactionnels, UMR CNRS 7651, Ecole Polytechnique, 91128 Palaiseau Cedex, France
^bLaboratoire Analyse et Environnement, UMR 8587, Bâtiment des Sciences, Université d’Evry, boulevard F. Mitterrand, 91025 Evry cedex, France

ABSTRACT:

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 ~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.

Keywords: No keywords available

You can buy this paper on-line in PDF format; it costs only £11.75. Just click on the BUY on-line button. You can pay on-line through a secure server and get access immediately.