Mechanism of interaction of novel uncharged, centrally active reactivators with OP-hAChE conjugates

Zoran Radić, Rakesh K. Sit, Edzna Garcia, Limin Zhang, Suzana Berend, Zrinka Kovarik, Gabriel Amitai, Valery V. Fokin, K. Barry Sharpless, Palmer Taylor

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

A library of more than 200 novel uncharged oxime reactivators was used to select and refine lead reactivators of human acetylcholinesterase (hAChE) covalently conjugated with sarin, cyclosarin, VX, paraoxon and tabun. N-substituted 2-hydroxyiminoacetamido alkylamines were identified as best reactivators and reactivation kinetics of the lead oximes, RS41A and RS194B, were analyzed in detail. Compared to reference pyridinium reactivators, 2PAM and MMB4, molecular recognition of RS41A reflected in its Kox constant was compromised by an order of magnitude on average for different OP-hAChE conjugates, without significant differences in the first order maximal phosphorylation rate constant k2. Systematic structural modifications of the RS41A lead resulted in several-fold improvement with reactivator, RS194B. Kinetic analysis indicated Kox reduction for RS194B as the main kinetic constant leading to efficient reactivation. Subtle structural modifications of RS194B were used to identify essential determinants for efficient reactivation. Computational molecular modeling of RS41A and RS194B interactions with VX inhibited hAChE, bound reversibly in Michaelis type complex and covalently in the pentacoordinate reaction intermediate suggests that the faster reactivation reaction is a consequence of a tighter RS194B interactions with hAChE peripheral site (PAS) residues, in particular with D74, resulting in lower interaction energies for formation of both the binding and reactivation states. Desirable in vitro reactivation properties of RS194B, when coupled with its in vivo pharmacokinetics and disposition in the body, reveal the potential of this oxime design as promising centrally and peripherally active antidotes for OP toxicity.

Original languageEnglish
Pages (from-to)67-71
Number of pages5
JournalChemico-Biological Interactions
Volume203
Issue number1
DOIs
Publication statusPublished - 25 Mar 2013
Externally publishedYes

Fingerprint

Acetylcholinesterase
Oximes
Kinetics
Sarin
Paraoxon
Reaction intermediates
Molecular recognition
Antidotes
Phosphorylation
Molecular modeling
Pharmacokinetics
RS194B
Libraries
Toxicity
Rate constants
RS41A

Keywords

  • CNS AChE reactivation
  • Molecular modeling
  • Organophosphate intoxication
  • Oxime reactivation
  • Peripheral site

ASJC Scopus subject areas

  • Toxicology

Cite this

Radić, Z., Sit, R. K., Garcia, E., Zhang, L., Berend, S., Kovarik, Z., ... Taylor, P. (2013). Mechanism of interaction of novel uncharged, centrally active reactivators with OP-hAChE conjugates. Chemico-Biological Interactions, 203(1), 67-71. https://doi.org/10.1016/j.cbi.2012.08.014

Mechanism of interaction of novel uncharged, centrally active reactivators with OP-hAChE conjugates. / Radić, Zoran; Sit, Rakesh K.; Garcia, Edzna; Zhang, Limin; Berend, Suzana; Kovarik, Zrinka; Amitai, Gabriel; Fokin, Valery V.; Barry Sharpless, K.; Taylor, Palmer.

In: Chemico-Biological Interactions, Vol. 203, No. 1, 25.03.2013, p. 67-71.

Research output: Contribution to journalArticle

Radić, Z, Sit, RK, Garcia, E, Zhang, L, Berend, S, Kovarik, Z, Amitai, G, Fokin, VV, Barry Sharpless, K & Taylor, P 2013, 'Mechanism of interaction of novel uncharged, centrally active reactivators with OP-hAChE conjugates', Chemico-Biological Interactions, vol. 203, no. 1, pp. 67-71. https://doi.org/10.1016/j.cbi.2012.08.014
Radić, Zoran ; Sit, Rakesh K. ; Garcia, Edzna ; Zhang, Limin ; Berend, Suzana ; Kovarik, Zrinka ; Amitai, Gabriel ; Fokin, Valery V. ; Barry Sharpless, K. ; Taylor, Palmer. / Mechanism of interaction of novel uncharged, centrally active reactivators with OP-hAChE conjugates. In: Chemico-Biological Interactions. 2013 ; Vol. 203, No. 1. pp. 67-71.
@article{385e84859dd64891ae5ad5fb090aba61,
title = "Mechanism of interaction of novel uncharged, centrally active reactivators with OP-hAChE conjugates",
abstract = "A library of more than 200 novel uncharged oxime reactivators was used to select and refine lead reactivators of human acetylcholinesterase (hAChE) covalently conjugated with sarin, cyclosarin, VX, paraoxon and tabun. N-substituted 2-hydroxyiminoacetamido alkylamines were identified as best reactivators and reactivation kinetics of the lead oximes, RS41A and RS194B, were analyzed in detail. Compared to reference pyridinium reactivators, 2PAM and MMB4, molecular recognition of RS41A reflected in its Kox constant was compromised by an order of magnitude on average for different OP-hAChE conjugates, without significant differences in the first order maximal phosphorylation rate constant k2. Systematic structural modifications of the RS41A lead resulted in several-fold improvement with reactivator, RS194B. Kinetic analysis indicated Kox reduction for RS194B as the main kinetic constant leading to efficient reactivation. Subtle structural modifications of RS194B were used to identify essential determinants for efficient reactivation. Computational molecular modeling of RS41A and RS194B interactions with VX inhibited hAChE, bound reversibly in Michaelis type complex and covalently in the pentacoordinate reaction intermediate suggests that the faster reactivation reaction is a consequence of a tighter RS194B interactions with hAChE peripheral site (PAS) residues, in particular with D74, resulting in lower interaction energies for formation of both the binding and reactivation states. Desirable in vitro reactivation properties of RS194B, when coupled with its in vivo pharmacokinetics and disposition in the body, reveal the potential of this oxime design as promising centrally and peripherally active antidotes for OP toxicity.",
keywords = "CNS AChE reactivation, Molecular modeling, Organophosphate intoxication, Oxime reactivation, Peripheral site",
author = "Zoran Radić and Sit, {Rakesh K.} and Edzna Garcia and Limin Zhang and Suzana Berend and Zrinka Kovarik and Gabriel Amitai and Fokin, {Valery V.} and {Barry Sharpless}, K. and Palmer Taylor",
year = "2013",
month = "3",
day = "25",
doi = "10.1016/j.cbi.2012.08.014",
language = "English",
volume = "203",
pages = "67--71",
journal = "Chemico-Biological Interactions",
issn = "0009-2797",
publisher = "Elsevier Ireland Ltd",
number = "1",

}

TY - JOUR

T1 - Mechanism of interaction of novel uncharged, centrally active reactivators with OP-hAChE conjugates

AU - Radić, Zoran

AU - Sit, Rakesh K.

AU - Garcia, Edzna

AU - Zhang, Limin

AU - Berend, Suzana

AU - Kovarik, Zrinka

AU - Amitai, Gabriel

AU - Fokin, Valery V.

AU - Barry Sharpless, K.

AU - Taylor, Palmer

PY - 2013/3/25

Y1 - 2013/3/25

N2 - A library of more than 200 novel uncharged oxime reactivators was used to select and refine lead reactivators of human acetylcholinesterase (hAChE) covalently conjugated with sarin, cyclosarin, VX, paraoxon and tabun. N-substituted 2-hydroxyiminoacetamido alkylamines were identified as best reactivators and reactivation kinetics of the lead oximes, RS41A and RS194B, were analyzed in detail. Compared to reference pyridinium reactivators, 2PAM and MMB4, molecular recognition of RS41A reflected in its Kox constant was compromised by an order of magnitude on average for different OP-hAChE conjugates, without significant differences in the first order maximal phosphorylation rate constant k2. Systematic structural modifications of the RS41A lead resulted in several-fold improvement with reactivator, RS194B. Kinetic analysis indicated Kox reduction for RS194B as the main kinetic constant leading to efficient reactivation. Subtle structural modifications of RS194B were used to identify essential determinants for efficient reactivation. Computational molecular modeling of RS41A and RS194B interactions with VX inhibited hAChE, bound reversibly in Michaelis type complex and covalently in the pentacoordinate reaction intermediate suggests that the faster reactivation reaction is a consequence of a tighter RS194B interactions with hAChE peripheral site (PAS) residues, in particular with D74, resulting in lower interaction energies for formation of both the binding and reactivation states. Desirable in vitro reactivation properties of RS194B, when coupled with its in vivo pharmacokinetics and disposition in the body, reveal the potential of this oxime design as promising centrally and peripherally active antidotes for OP toxicity.

AB - A library of more than 200 novel uncharged oxime reactivators was used to select and refine lead reactivators of human acetylcholinesterase (hAChE) covalently conjugated with sarin, cyclosarin, VX, paraoxon and tabun. N-substituted 2-hydroxyiminoacetamido alkylamines were identified as best reactivators and reactivation kinetics of the lead oximes, RS41A and RS194B, were analyzed in detail. Compared to reference pyridinium reactivators, 2PAM and MMB4, molecular recognition of RS41A reflected in its Kox constant was compromised by an order of magnitude on average for different OP-hAChE conjugates, without significant differences in the first order maximal phosphorylation rate constant k2. Systematic structural modifications of the RS41A lead resulted in several-fold improvement with reactivator, RS194B. Kinetic analysis indicated Kox reduction for RS194B as the main kinetic constant leading to efficient reactivation. Subtle structural modifications of RS194B were used to identify essential determinants for efficient reactivation. Computational molecular modeling of RS41A and RS194B interactions with VX inhibited hAChE, bound reversibly in Michaelis type complex and covalently in the pentacoordinate reaction intermediate suggests that the faster reactivation reaction is a consequence of a tighter RS194B interactions with hAChE peripheral site (PAS) residues, in particular with D74, resulting in lower interaction energies for formation of both the binding and reactivation states. Desirable in vitro reactivation properties of RS194B, when coupled with its in vivo pharmacokinetics and disposition in the body, reveal the potential of this oxime design as promising centrally and peripherally active antidotes for OP toxicity.

KW - CNS AChE reactivation

KW - Molecular modeling

KW - Organophosphate intoxication

KW - Oxime reactivation

KW - Peripheral site

UR - http://www.scopus.com/inward/record.url?scp=84875809406&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84875809406&partnerID=8YFLogxK

U2 - 10.1016/j.cbi.2012.08.014

DO - 10.1016/j.cbi.2012.08.014

M3 - Article

VL - 203

SP - 67

EP - 71

JO - Chemico-Biological Interactions

JF - Chemico-Biological Interactions

SN - 0009-2797

IS - 1

ER -