Naslov
Amino acids residues involved in cholinesterase inhibition with isoproterenol and its carbamate

Autori
Bosak, Anita ; Gazić, Ivana ; Vinković, Vladimir ; Kovarik, Zrinka

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

Izvornik
Book of Abstracts of the HDBMB 2008, Congress of the Croatian Society of Biochemistry and Molecular Biology with international participation / Strelec, Ivica ; Glavaš-Obrovac, Ljubica - Osijek : Hrvatsko Društvo za Biotehnologiju, 2008, 72-72

ISBN
978-953-95551-2-0

Skup
HDBMB 2008, Congress of the Croatian Society of Biochemistry and Molecular Biology with International Participation

Mjesto i datum
Osijek, Hrvatska, 17.09.2008. - 20.09.2008

Vrsta sudjelovanja
Poster

Vrsta recenzije
Domaća recenzija

Ključne riječi
isoproterenol; carbamate; AChE; mutants; affinity; selectivity

Sažetak
Isoproterenol, a sympathomimetic beta adrenergic receptor agonist used to treat asthma, and its dimethylcarbamate ester were studied as inhibitors of mouse recombinant acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and six AChE mutants. Carbamate of isoproterenol carbamylates the active site serine and progressively inhibits cholinesterases, while isoproterenol, the final product of decarbamylation, is reversible inhibitor of cholinesterases. Mutations in the choline binding site (Y337A) combined with those in the acyl pocket (F295L/Y337A, F297I/Y337A, F295L/F297I/Y337A) or in the peripheral site (Y124Q and Y72N/Y124Q/W286R) were employed to mimic BChE active site residues. The aim was to identify amino acids that governed the inhibition with isoproterenol and isoproterenol carbamate by determining dissociation and inhibition rate constants, respectively. Competitive inhibition was observed for AChE w.t. and peripheral site mutants, and non-competitive inhibition for BChE and choline binding site and acyl pocket mutants. All studied cholinesterases displayed poor affinity for isoproterenol (K(I)=0.12 – 2.3 mM), yet BChE had a three times higher affinity than AChE. Although mutations in the choline binding site and acyl pocket mimics BChE, affinities of these mutants were up to six times higher than that of BChE. Peripheral site mutants had only slightly higher affinity than AChE w.t. The selectivity of BChE for isoproterenol binding is mainly governed by residues Ala337 and Ile297. The bimolecular rate constant of BChE inhibition by isoproterenol carbamate was 36 times higher than that of AChE. All mutants, except F297I, had higher inhibition rates than AChE w.t. (up to 13 times for F295L/Y337A) and therefore lower selectivity of the wild-type enzymes. It seems that Phe295 and residues of the peripheral site are the key residues for cholinesterase selectivity for isoproterenol carbamate.

Izvorni jezik
Engleski

Znanstvena područja
Kemija, Temeljne medicinske znanosti

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