title: A reevaluation of computed proton affinities for the common alpha-amino acids.
abstract: The proton affinities of the 20 common amino acids have been computed at the G3MP2 level using structures derived from broad conformational searches at a variety of levels including G3MP2. In some cases, the conformational surveys identified more stable species than had been used in previous studies of proton affinities, though the differences in energy are sometimes rather small. The present values are likely the most reliable measure of amino acid proton affinities in the gas phase. An analysis of differences between these values and those obtained experimentally via the kinetic method indicates that the extraction of proton affinities from kinetic method data can potentially lead to large errors linked to the estimation of relative protonation entropies.
authors.affiliation: Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, USA. sgronert@vcu.edu
authors.forename: Scott
authors.initials: S
authors.lastname: Gronert
authors.forename: David C
authors.initials: DC
authors.lastname: Simpson
authors.forename: Keyanna M
authors.initials: KM
authors.lastname: Conner
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D019295:Computational Biology / Q000379:methods; D005740:Gases / Q000737:chemistry; D007700:Kinetics; D044367:Phase Transition; D011487:Protein Conformation; D011522:Protons; D013816:Thermodynamics
chemical_list: D000596:Amino Acids; D005740:Gases; D011522:Protons
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