Gas-phase basicity of glycine, alanine, proline, serine, lysine, histidine and some of their peptides by the thermokinetic method.
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.
Bouchoux
G
G
Laboratoire des Mécanismes Réactionnels, UMR CNRS 7651, Ecole Polytechnique, 91128 Palaiseau Cedex, France.
Salpin
J-Y
JY
D000409:Alanine / Q000737:chemistry; D000596:Amino Acids / Q000737:chemistry*; D005740:Gases / Q000737:chemistry*; D005998:Glycine / Q000737:chemistry; D006639:Histidine / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008239:Lysine / Q000737:chemistry; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry*; D011392:Proline / Q000737:chemistry; D011522:Protons; D012694:Serine / Q000737:chemistry; D013816:Thermodynamics
D000596:Amino Acids; D005740:Gases; D010455:Peptides; D011522:Protons; D012694:Serine; D006639:Histidine; D011392:Proline; D008239:Lysine; D000409:Alanine; D005998:Glycine