Enantioseparation, in vitro testing, and structural characterization of triple-binding reactivators of organophosphate-inhibited cholinesterases. Issue 15 (7th August 2020)

• Record Type: Journal Article
• Authors: Maraković, Nikola; Knežević, Anamarija; Rončević, Igor; Brazzolotto, Xavier; Kovarik, Zrinka; Šinko, Goran
• Is Part Of: Biochemical journal. Volume 477:Issue 15(2020)
• Page Start: 2771
• Page End: 2790
• Publication Date: 2020-08-07
• Subjects: cholinesterase -- hydroxyiminoacetamide -- PM7R6 method -- reactivation -- stereoselectivity; Biochemistry -- Periodicals; 572
• DOI: 10.1042/BCJ20200192
• Languages: English
• ISSNs: 0264-6021

Abstract

Abstract : The enantiomers of racemic 2-hydroxyimino- N -(azidophenylpropyl)acetamide-derived triple-binding oxime reactivators were separated, and tested for inhibition and reactivation of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibited with tabun (GA), cyclosarin (GF), sarin (GB), and VX. Both enzymes showed the greatest affinity toward the methylimidazole derivative (III ) of 2-hydroxyimino- N -(azidophenylpropyl)acetamide (I ). The crystal structure was determined for the complex of oxime III within human BChE, confirming that all three binding groups interacted with active site residues. In the case of BChE inhibited by GF, oximes I ( k r = 207 M −1 min −1 ) and III ( k r = 213 M −1 min −1 ) showed better reactivation efficiency than the reference oxime 2-PAM. Finally, the key mechanistic steps in the reactivation of GF-inhibited BChE with oxime III were modeled using the PM7R6 method, stressing the importance of proton transfer from Nε of His438 to Oγ of Ser203 for achieving successful reactivation.