Naslov
Kinetics of interaction of ethopropazine enatiomers with butyrylchopolinesterase and acetylcholinesterase

Autori
Šinko, Goran ; Radić, Zoran ; Simeon-Rudolf, Vera ; Reiner, Elsa ; Taylor, Palmer

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
XIth International Symposium on Cholinergic Mechanisms-Function and Disfunction & 2nd Misrahi Symposium on Neurobiology, St Moritz, Švicarska, Program and Abstracts / - Sankt Moritz, 2002, 33-33

Skup
Mechanisms-Function and Disfunction & 2nd Misrahi Symposium on Neurobiology, St Moritz, Švicarska

Mjesto i datum
St. Moritz, Švicarska, 05.05.2002. - 09.05.2002

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
butyrylcholinesterase; acetylcholinesterase; ethopropazine; binding sites

Sažetak
The association and dissociation rates of (+)ethopropazine and (-) ethopropazine with wild-type mouse and horse butyrylcholinesterases (BChE), and mutant mouse acetylcholinesterase (AChE) were studied in order to analyze elements of stereo selectivity in two similar but distinct enzyme templates. Reaction traces at 23 oC in 0.1 M phosphate buffer pH 7.0 were recorded in millisecond time frame using Applied Photophysics stopped-flow apparatus equipped with fluorescence detection. Dissociation rate constants evaluated for BChEs were three to four-fold faster for (-)enantiomer (130 (1/min) vs. 30 (1/min) for horse BChE) , while association rate constants for enantiomers were similar (1.4 (1/nM*min) vs. 1.0 (1/nM*min) for horse BChE), resulting in lower equilibrium dissociation constant and better binding of (+) ethopropazine with BChE. In the AChE template the preferential binding of (+)ethopropazine was observed with Tyr337Ala mutant, but with an order of magnitude greater stereo specificity. Binding preference for Tyr124Gln AChE mutant, however, was inversed and (-)ethopropazine (Kd of about 1.8 uM ) bound several fold better than (+)enantiomer. Inhibition of enzymic acetylthiocholine hydrolysis by ethopropazine enantiomers yielded equilibrium inhibition constants similar to equilibrium dissociation constants derived from stopped-flow rate measurements. In conclusion, active center gorge of AChE, lined with larger number of aromatic residues than the gorge of BChE, provides narrower and more stereo selective environment for binding of ethopropazine.

Izvorni jezik
Engleski

Znanstvena područja
Temeljne medicinske znanosti

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