Acetylcholinesterase: A Pretreatment Drug for Organophosphate Toxicity

Doctor, Bhupendra P.; Blick, Dennis W.; Gentry, Mary K.; Maxwell, Donald M.; Miller, Stephanie A.; Murphy, Michael R.; Wolfe, Alan D.

doi:10.1007/978-1-4615-3046-6_36

Cited by 2 publications

(2 citation statements)

References 14 publications

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“…The high reactivity of the enzyme toward organophosphorus compounds suggests that exogenous cholinesterase can serve as an effective therapeutic agent in the prophylaxis and treatment of organophosphorus poisoning. Indeed the successful exploitation of the scavenging potential of administered cholinesterase has been demonstrated in rodents and in non-human primates [1][2][3][4][5]. The use of human AChE (HuAChE) as an efficient bioscavenger has been advanced by the development of recombinant production systems [6][7][8], and the introduction of catalytically favourable mutations [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Effect of chemical modification of recombinant human acetylcholinesterase by polyethylene glycol on its circulatory longevity

et al. 2001

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Post-translational modifications were recently shown to be responsible for the short circulatory mean residence time (MRT) of recombinant human acetylcholinesterase (rHuAChE) [Kronman, Velan, Marcus, Ordentlich, Reuveny and Shafferman (1995) Biochem. J. 311, 959--967; Chitlaru, Kronman, Zeevi, Kam, Harel, Ordentlich, Velan and Shafferman (1998) Biochem. J. 336, 647--658; Chitlaru, Kronman, Velan and Shafferman (2001) Biochem. J. 354, 613--625], which is one of the major obstacles to the fulfilment of its therapeutic potential as a bioscavenger. In the present study we demonstrate that the MRT of rHuAChE can be significantly increased by the controlled attachment of polyethylene glycol (PEG) side chains to lysine residues. Attachment of as many as four PEG molecules to monomeric rHuAChE had minimal effects, if any, on either the catalytic activity (K(m)=0.09 mM and k(cat)=3.9 x 10(5) min(-1)) or the reactivity of the modified enzyme towards active-centre inhibitors, such as edrophonium and di-isopropyl fluorophosphate, or to peripheral-site ligands, such as propidium, BW284C51 and even the bulky snake-venom toxin fasciculin-II. The increase in MRT of the PEG-modified monomeric enzyme is linearly dependent, in the tested range, on the number of attached PEG molecules, as well as on their size. It appears that even low level PEG-conjugation can overcome the deleterious effect of under-sialylation on the pharmacokinetic performance of rHuAChE. At the highest tested ratio of attached PEG-20000/rHuAChE (4:1), an MRT of over 2100 min was attained, a value unmatched by any other known form of recombinant or native serum-derived AChE reported to date.

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Section: Introductionmentioning

confidence: 99%

Effect of chemical modification of recombinant human acetylcholinesterase by polyethylene glycol on its circulatory longevity

et al. 2001

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“…The current treatment regimes against nerve agent exposure are designed to protect life but are not able to prevent severe incapacitation. The high reactivity of ChEs towards OP-agents led to propose these biomolecules as exogenous scavengers for sequestration of toxic OP-agents before they reach their physiological target (Wolfe et al, 1987;Raveh et al, 1989;Broomfield et al, 1991;Doctor et al, 1992). The AChEs react irreversibly and on a molar basis, with the OP agents and therefore, the amounts of AChE required for treatment are high.…”

Section: General Introductionmentioning

confidence: 99%

Generation of Recombinant Human Ache Op-Scavengers With Extended Circulatory Longevity

Shafferman¹

2004

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of infomation. Send co.mments regarding this burden estimate or any other aspect of this colledion of information, including suggestions for reducing this burden to Washington Headquarters Sen/ices, Directorate Ibr Infbmialion Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Papenvork Reduction Project (0704-01881, Washington, DC 20503 Agency Use Only (Leave blank). 11. Supplementary Notes (i.e., report contains color photos, report contains appendix in non-print form, etc.)Original contains color plates: All DTIC reproductions will be in black and white. 12a. Distribution/Availability Statement)Approved for public release; distribution unlimited Abstract {Maximum 200 Words) 12b. Distribution Code (Leave Blank)The use of recombinant human acetylcholinesterase as an effective bioscavenger of organophosphorus compounds requires that it reside in the circulation for sufficiently long periods of time. We have demonstrated in the past that extension of the circulatory lifetime of AChE can be achieved either by optimizing post-translation-related enzyme processing or by chemical conjugation of polyethylene glycol (PEG) moieties to the enzyme. To delineate the interrelationship between these two modes of AChE modulation with regard to pharmacokinetic behavior, an array of AChE molecules differing in their post-translation-related processing was subjected to PEG-conjugation and monitored for their pharmacokinetic performance. In all cases tested to date, PEG-conjugation was found to give rise to enzyme species which reside for very long periods of time in the circulation of mice in a nearly equal manner. We have now found a novel mode of AChE circulatory elimination based on the recognition of specific amino acid-related epitopes. This unique clearance mechanism can also be efficiently overcome by enzyme PEGylation. These findings indicate that the circulatory residence is dictated primarily by the PEG appendage, and that cost-effective microorganisms-based production systems which do not support animal-cell-related enzyme processing, may be utilized for large-scale AChE production. In line with this notion, we have constructed a synthetic human AChE gene designed for optimal expression in microorganism-based production systems, which will now be tested for its ability to sustain human AChE production.14. Subject Terms (keywords previously assigned to proposal abstract or terms which apply to this award) I. GENERAL INTRODUCTIONThe primary role of acetylcholinesterase (acetylcholine acetylhydrolase 3.1.1.7, AChE) is the termination of impulse transmission in cholinergic synapses by rapid hydrolysis of the neurotransmitter acetylchoUne (ACh). The enzyme has been th...

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Acetylcholinesterase: A Pretreatment Drug for Organophosphate Toxicity

Cited by 2 publications

References 14 publications

Effect of chemical modification of recombinant human acetylcholinesterase by polyethylene glycol on its circulatory longevity

Effect of chemical modification of recombinant human acetylcholinesterase by polyethylene glycol on its circulatory longevity

Generation of Recombinant Human Ache Op-Scavengers With Extended Circulatory Longevity

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