Mechanism for potent reactivation ability of H oximes analyzed by reactivation kinetic studies with cholinesterases from different species
Oxime-induced reactivation of organophosphorus (OP) nerve agent-inhibited acetylcholinesterase (AChE) is a very important step for the treatment of nerve agent toxicity. Therefore, extensive efforts are being made to develop more efficient and broad-spectrum oximes to replace the currently used oxim...
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Published in | Chemico-biological interactions Vol. 187; no. 1; pp. 185 - 190 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Ireland
Elsevier Ireland Ltd
06.09.2010
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Subjects | |
Online Access | Get full text |
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Summary: | Oxime-induced reactivation of organophosphorus (OP) nerve agent-inhibited acetylcholinesterase (AChE) is a very important step for the treatment of nerve agent toxicity. Therefore, extensive efforts are being made to develop more efficient and broad-spectrum oximes to replace the currently used oximes 2-PAM or obidoxime. In the 1970s and 1980s, several H oximes (such as HI-6 and HLo-7) were found to be very potent reactivators of non-aged soman-inhibited AChE. Later these oximes were shown to rapidly reactivate GF- and VR-inhibited AChE as well. However, the mechanism for the high potency of these H oximes is still unknown. In this study, the relationship between the reactivation rate constant of nerve agent-inhibited rhesus monkey AChE, human AChE and guinea pig AChE and the size of the alkoxyl (OR) group of nerve agents was analyzed. Results demonstrate that for nerve agent-inhibited rhesus monkey and human AChEs, reactivation by H oximes accelerated as the size of the OR group was increased. But with guinea pig AChE, reactivation by H oximes declined as the size of the OR group was increased. Reactivation kinetic study using GF- and VR-inhibited wild-type and mutant bovine AChEs has shown that mutations of Y124Q and W286A particularly reduced reactivation by these H oximes. Since these 2 amino acid residues are highly conserved in all AChEs sequenced to date, it is unlikely that the remarkable reduction observed in H oxime reactivation with guinea pig AChE is caused by a change in these two amino acid residues. |
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ISSN: | 0009-2797 1872-7786 |
DOI: | 10.1016/j.cbi.2010.01.018 |