| Acid-base thermochemistry of gaseous aliphatic α-aminoacids. | |
| | |
MedLine Citation:
|
PMID: 21038045 Owner: NLM Status: In-Process |
Abstract/OtherAbstract:
|
Acid-base thermochemistry of isolated aliphatic amino acids (denoted AAA): glycine, alanine, valine, leucine, isoleucine and proline has been examined theoretically by quantum chemical computations at the G3MP2B3 level. Conformational analysis on neutral, protonated and deprotonated species has been used to identify the lowest energy conformers and to estimate the population of conformers expected to be present at thermal equilibrium at 298 K. Comparison of the G3MP2B3 theoretical proton affinities, PA, and ΔH(acid) with experimental results is shown to be correct if experimental thermochemistry is re-evaluated and adapted to the most recent acidity-basicity scales. From this point of view, a set of evaluated proton affinities of 887, 902, 915, 916, 919 and 941 kJ mol(-1), and a set of evaluated ΔH(acid) of 1433, 1430, 1423, 1423, 1422 and 1426 kJ mol(-1), is proposed for glycine, alanine, valine, leucine, isoleucine and proline, respectively. Correlations with structural parameters (Taft's σ(α) polarizability parameter and molecular size) suggest that polarizability of the side chain is the major origin of the increase in PA and decrease in ΔH(acid) along the homologous series glycine, alanine, valine and leucine/isoleucine. Heats of formation of gaseous species AAA, AAAH(+) and [AAA-H](-) were computed at the G3MP2B3 level. The present study provides previously unavailable Δ(f)H°(298) for the ionized species AAAH(+) and [AAA-H](-). Comparison with Benson's estimate, and correlation with molecular size, show that several experimental Δ(f)H°(298) values of neutral or gaseous AAA might be erroneous. |
| | |
Authors:
|
Guy Bouchoux; Sihua Huang; Bhawani Singh Inda |
Related Documents
:
|
8167365 - Amino acid residues required for the activity of avrd alleles. 10785375 - Utilization of leucine and acetate as carbon sources for sterol and fatty acid biosynth... 2117095 - Plasma and muscle free amino acids in maintenance hemodialysis patients without protein... 14197885 - Valine-isoleucine metabolism in acetobacter suboxydans and the inhibition of growth by ... 8167365 - Amino acid residues required for the activity of avrd alleles. 12054945 - Regio- and stereoselective ring openings of 3-aza-2-oxabicyclo[2.2.1]hept-5-ene systems... |
Publication Detail:
|
Type: Journal Article Date: 2010-10-29 |
Journal Detail:
|
Title: Physical chemistry chemical physics : PCCP Volume: 13 ISSN: 1463-9084 ISO Abbreviation: Phys Chem Chem Phys Publication Date: 2011 Jan |
Date Detail:
|
Created Date: 2010-12-17 Completed Date: - Revised Date: - |
Medline Journal Info:
|
Nlm Unique ID: 100888160 Medline TA: Phys Chem Chem Phys Country: England |
Other Details:
|
Languages: eng Pagination: 651-68 Citation Subset: IM |
Affiliation:
|
Laboratoire des Mécanismes Réactionnels, UMR CNRS 7651, Département de Chimie, Ecole Polytechnique, F-91128 Palaiseau cedex, France. bouchoux@dcmr.polytechnique.fr |
Export Citation:
|
APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
|
|
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
Previous Document: The use of Br/Cl to promote regioselective gold-catalyzed rearrangement of propargylic carboxylates:...
Next Document: Optical properties of ZnO nanostructures: a hybrid DFT/TDDFT investigation.