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Original scientific paper

https://doi.org/10.5562/cca1829

Influence of the Acyl Moiety on the Hydrolysis of Quinuclidinium Esters Catalyzed by Butyrylcholinesterase

Ines Primožič ; Department of Chemistry, Faculty of Science, University of Zagreb Horvatovac 102a, HR-10000 Zagreb, Croatia
Srđanka Tomić ; Department of Chemistry, Faculty of Science, University of Zagreb Horvatovac 102a, HR-10000 Zagreb, Croatia


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Abstract

Eight chiral esters of quinuclidin-3-ol and butyric, acetic, pivalic and benzoic acid were synthesized
as well as their racemic and chiral, quaternary N-benzyl derivatives. All racemic and chiral quaternary
compounds were studied as substrates and/or inhibitors of horse serum butyrylcholinesterase
(BChE). The best substrate for the enzyme was (R)-N-benzyl butyrate. The rates of hydrolysis decreased
in order (R)-butyrate >> (R)-acetate (7-fold slower) > (R)-pivalate (8-fold slower) > (R)-benzoate (9-fold
slower reaction), while (S)-N-benzyl esters were much poorer substrates (320 (butyrate) - 4360-fold slower
(pivalate) than the appropriate (R)-enantiomer). For all (S)-N-benzyl esters excluding (S)-N-benzyl acetate
inhibition constants were determined (Ka = 3.3−60 μmol dm−3). The hydrolysis of racemic mixtures of
N-benzyl esters proceeded 1.4 (for acetate) − 5.1 (for benzoate) times slower than that of pure (R)-
enantiomers of the corresponding concentrations due to the inhibition with (S)-enantiomers. Change of the
acyl moiety of the substrate effected both activity and stereoselectivity of the BChE.(doi:
10.5562/cca1829)

Keywords

esters of quinuclidin-3-ol, enzymic resolution, butyrylcholinesterase, hydrolysis kinetics, inhibition constants

Hrčak ID:

71987

URI

https://hrcak.srce.hr/71987

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