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  • Mechanism of stereoselective interaction between butyrylcholinesterase and ethopropazine enantiomers
    Šinko, Goran ...
    Stereoselectivity of reversible inhibition of butyrylcholinesterase (BChE; EC 3.1.1.8) by optically pure ethopropazine š10-(2-diethylaminopropyl)phenothiazine hydrochlorideđ enantiomers and racemate ... was studied with acetylthiocholine (0.002-250 mM) as substrate. Molecular modelling resulted in the reaction between BChE and ethopropazine starting with the binding of ethopropazine to the enzyme peripheral anionic site. In the next step ethopropazine 'slides down' the enzyme gorge, resulting in interaction of the three rings of ethopropazine through pi-pi interactions with W82 in BChE. Inhibition mechanism was interpreted according to three kinetic models: A, B and C. The models differ in the type and numberof enzyme-substrate, enzyme-inhibitor and enzyme-substrate-inhibitor complexes, i.e., presence of the Michaelis complex and/or acetylated BChE. Although, all three models reproduced well the BChE activity in absence of ethopropazine, model A was poor in describing inhibition with ethopropazine, while models B and C were better, especially for substrate concentrations above 0.2 mM. However model C was singled out because it approaches fulfilmentof the one step-one event criteria, and confirms the inhibition mechanism derived from molecular modelling. Model C resulted in dissociation constants for the complex between BChE and ethopropazine: 61, 140 and 88 nM for R-enantiomer, S-enantiomer and racemate, respectively. The respective dissociation constants for the complexes between acetylated BChE and ethopropazine were 268, 730 and 365 nM. Butyrylcholinesterase had higher affinity for R-ethopropazine.
    Vir: Biochimie. - ISSN 0300-9084 (Vol. 93, issue 10, 2011, str. 1797-1806)
    Vrsta gradiva - članek, sestavni del
    Leto - 2011
    Jezik - angleški
    COBISS.SI-ID - 28808409
    DOI

vir: Biochimie. - ISSN 0300-9084 (Vol. 93, issue 10, 2011, str. 1797-1806)
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