Naslov
Mutagenesis and new oximes enable reactivation of tabun-inhibited acetylcholinesterases

Autori
Kovarik, Zrinka ; Kalisiak, Jarosław ; Maček, Nikolina ; Katalinić, Maja ; Berend, Suzana ; Radić, Zoran ; Fokin, Valery V. ; Sharpless, Barry K. ; Taylor, Palmer

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

Izvornik
Book of Abstracts of the FEBS3+ Meeting ˝From molecules to life and back˝, Opatija, Hrvatska / Dumić, Jerka ; Kovarik, Zrinka ; Varljen, Jadranka - Rijeka : Hrvatsko Društvo za Biotehnologiju, 2012

ISBN
978-953-95551-4-4

Skup
FEBS3+ Meeting: From molecules to life and back

Mjesto i datum
Opatija, Hrvatska, 13.06.2012. - 16.06.2012

Vrsta sudjelovanja
Pozvano predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
reactivation; mutants; oximes; tabun

Sažetak
Acetylcholinesterase (AChE, EC 3.1.1.7), an important enzyme in cholinergic neurotransmission, is the primary target of organophosphorus compounds (OP) like pesticides and nerve agents such as tabun. A library of new oximes was screened for the reactivation activity of tabun- inhibited human recombinant AChE. Fifty-three out of 100 oximes reactivated wild type AChE, but only 14 of them restored full activity. Within this series, it appears that an approximate distance equivalent to 8 methylenes between two quaternary nitrogens achieved an optimal level of AChE reactivation. The mutant, Y337A, at the choline binding site was reactivated by more than 80% with only 13 of the oximes. The most efficient reactivators of Y337A appeared to be 2PAM analogs, with maximal reactivation rate constants kmax up to 10 times faster than those determined for the most efficient reactivator of AChE w.t. Although introducing an additional mutation into the Y337A choline binding site in double mutant Y337A/F338A reduced the enhancement observed in the Y337A mutant, the most efficient Y337A/F338A reactivators also contained the 8 methylene equivalence between two quaternary nitrogens as found for the wild type. It seems that, on average, the modification of the active site in the double mutant compromised molecular recognition reflected in the Kox constant, but slightly improved the maximal reactivation rate constant kmax. Since all oximes were designed as reactivators of phosphorylated AChE, a limited reactivation capacity for related butyrylcholinesterase (BChE, EC 3.1.1.8) was expected. However, 37 oximes reactivated tabun- inhibited BChE more efficiently than 2PAM, and five reached maximal reactivation of 70 %. In addition, toxicity and antidotal studies with lead reactivators in mice showed significantly improved protective indexes in therapy upon tabun exposure compared to the standard antidote, 2PAM. Therefore, our findings offer a platform for further development of more potent congenic antidotes in tabun and related phosphoramidate exposure.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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