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Enantioselectivity of the Pseudomonas cepacia lipase towards 2-methyl-3-(or 4)-arylalkanols: an approach based on stereoelectronic theory and the molecular modeling

For a better understanding of the previously reported enantiose-lectivity of Pseudomonas cepacia lipase (PCL) in acylation of racemic primary alcohols, 2-methyl-3(or 4)-arylalkanols, molecular model-ing of tetrahedral intermediates (TIs) at the active site was per-formed. The most probable conformers of TIs were elucidated and their interactions with the amino acid residues of the binding pockets at the enzyme active site were studied. The free energy difference between TIs of two enantiomers was approximated by the differ-ences in potential energy and the solvent accesible surface area. Correlation between the H
(His286) … O(Ser87) hydrogen bond dif-ferences of diastereomeric, low energy gauche-TIs, and experimen-tally determined enantiomeric ratios was found. In agreement with the stereoelectronic theory, the gauche-TI precedes ester release.

Pseudomonas cepacia lipase; kinetic resolution; primary alcohols; enantioselectivity; molecular modeling; stereoelectronic theory

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