Conformation-reactivity relationships in pyridoxal model systems: A semiempirical molecular mechanics and MO-LCAO investigation

A preliminary investigation on the torsional hypersurface of the alanine Schiff bases with salicylaldehyde and pyridoxal was carried out by means of a van der Waals potential calculation. This allowed location of a few stable conformers, which were then subjected to a PCILO optimization. On the lowe...

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Bibliographic Details
Published in:Bioorganic chemistry 1988, Vol.16 (2), p.133-148
Main Authors: Villa, A.M., Casella, L., Fantucci, P.
Format: Article
Language:English
Subjects:
biochemistry
computers
pyridoxine
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Summary:A preliminary investigation on the torsional hypersurface of the alanine Schiff bases with salicylaldehyde and pyridoxal was carried out by means of a van der Waals potential calculation. This allowed location of a few stable conformers, which were then subjected to a PCILO optimization. On the lowest energy conformer, an electrostatic molecular potential map was generated through a CNDO/2 calculation. Another pyridoxal model system, where the N-pyridoxylidene-alanine Schiff base is coordinated to a metal ion, was examined in order to check the relationship between the conformation at the amino acid α-carbon atom and the reactivity toward the C αH proton abstraction process. It has been found that the highest energy conformer containing a pseudoaxial C αH bond produces the most stable base adduct and carbanion species, in agreement with Dunathan's hypothesis. The potential biological significance of these results is discussed.
ISSN:0045-2068
1090-2120
DOI:10.1016/0045-2068(88)90003-X