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Internet Electronic Journal of Molecular Design - IEJMD, ISSN 1538-6414, CODEN IEJMAT
| ABSTRACT - Internet Electron. J. Mol. Des. January 2006, Volume 5, Number 1, 27-48 |
A Theoretical Study of Structures and Unimolecular Decomposition
Pathways of Pyruvic Acid
Rita Kakkar, Preeti Chadha, and Deepshikha Verma
Internet Electron. J. Mol. Des. 2006, 5, 27-48
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Abstract:
Pyruvic acid occurs naturally in the body and is the end product
of the metabolism of sugar and starch. Its thermal
decarboxylation reaction is important as it prevents the build-up
of lactic acid in the body due to excess of pyruvic acid. However,
in spite of its biochemical importance, very little is known of the
structure of pyruvic acid and its decarboxylation reactions, as
well as its enzymatic pathways. It was therefore considered
necessary to carry out a thorough study of its reactions using a
semiempirical method to test the validity of the approach, so that
it could be used for studying the enzymatic pathways of pyruvic
acid. The PM3 method was used for these calculations.
Equilibrium geometries of all possible conformers and tautomers
of pyruvic acid were calculated, and the geometries and
calculated vibrational spectra compared with experimental data.
Various decarboxylation reactions were explored and their final
products discussed. The keto form of pyruvic acid is the most
important tautomer on the potential energy surface. The lowest
energy decarboxylation pathway involves the formation of
hydroxyethylidene, which then isomerizes to the more stable
acetaldehyde. The results from these calculations are in
agreement with those from accurate ab initio calculations, as
well as experimental results, and this method may be profitably
used for calculations of the enzymatic pathways of pyruvic acid,
for which ab initio results are difficult owing to the large amount
of computer time required.
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