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Updated: Jul 14, 2026

Preparation and In Vivo Use of an Activity-based Probe for N-acylethanolamine Acid Amidase
Published on: November 23, 2016
Structure-activity approach in the reactivation of tabun-phosphorylated human acetylcholinesterase with bispyridinium
Zrinka Kovarik1, Maja Calić, Goran Sinko
1Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000 Zagreb, Croatia. zkovarik@imi.hr
Abstract:
We investigated interactions of bispyridinium para-aldoximes N,N'-(propano)bis(4-hydroxyiminomethyl) pyridinium bromide (TMB-4), N,N'-(ethano)bis(4-hydroxyiminomethyl)pyridinium methanosulphonate (DMB-4), and N,N'-(methano)bis(4-hydroxyiminomethyl)pyridinium chloride (MMB-4) with human erythrocyte acetylcholinesterase phosphorylated by tabun. We analysed aldoxime conformations to determine the flexibility of aldoxime as an important feature for binding to the acetylcholinesterase active site. Tabun-inhibited human erythrocyte acetylcholinesterase was completely reactivated only by the most flexible bispyridinium aldoxime - TMB-4 with a propylene chain between two rings. Shorter linkers than propylene (methylene or ethylene) as in MMB-4 and DMB-4 did not allow appropriate orientation in the active site, and MMB-4 and DMB-4 were not efficient reactivators of tabun-phosphorylated acetylcholinesterase. Since aldoximes are also reversible inhibitors of native acetylcholinesterase, we determined dissociation constants and their protective index against acetylcholinesterase inactivation by tabun.
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