Naslov
Phosphonylation of acetylcholinesterase and the propensity for reactivation analyzed by chirality and mutagenesis

Autori
Kovarik, Zrinka ; Radić, Zoran ; Berman, Harvey A. ; Taylor, Palmer

Vrsta, podvrsta i kategorija rada
Radovi u zbornicima skupova, cjeloviti rad (in extenso), znanstveni

Izvornik
Cholinergic mechanisms : Function and Dysfunction : Proceedings of the XIth ISCM / Fisher, Abraham ; Silman, Israel ; Soreq, Hermona ; Anglister, Lili ; Michaelson, Daniel M. - London : Delhi : Francis & Taylor, 2004, 611-612

ISBN
1841840750

Skup
XIth International Symposium on Cholinergic Mechanisms - Function and Dysfunction and 2nd Misrahi Symposium on Neurobiology

Mjesto i datum
St. Moritz, Švicarska, 05.05.2002. - 09.05.2002

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
acetylcholinesterase; reactivation; oximes

Sažetak
Mouse acetylcholinesterase (AChE) and its mutants were inhibited with Sp- and Rp- cycloheptyl- (CHMP), isopropyl- (iPrMP), and 3, 3-dimethylbutyl- (DMBMP) methylphosphonyl thiocholine enantiomers. Double and triple mutants of AChE had combined substitutions in the acyl pocket (F295L, F297I), choline binding site (Y337A, F338A) and in the active site residue, neighbouring the catalytic serine, E202Q. The Sp-enantiomers of the methylphosphonate esters are more reactive in forming the conjugate with AChE than Rp-enantiomers. The majority of combined mutants, however, were inhibited by Sp isomers at slower rates than the wild type AChE. Opening of the choline binding site by mutations Y337A/F338A enhanced inhibition rates 2-fold for all inhibitors except for Sp-CHMP which inhibited the mutant at a similar rate as wild type AChE. On the other hand, modification of aromatic residues in the active centre of AChE into aliphatic residues found in butyrylcholinesterase, F295L, F297I and Y337A, enhance inhibition of Rp isomers thus approaching inhibition rates of butyrylcholinesterase. Upon the F297I/Y337A mutations, Rp enantiomers of CHMP and iPrMP became more reactive than Sp enantiomers while reaction with the Sp enantiomers was slightly reduced, displaying inverted stereospecificity. Similar multiple mutations at these positions have been analysed for reactivation by the oximes, 2-PAM and HI-6. Similar to the inactivation rates, the Sp formed conjugates show the more rapid reactivation rates. Certain multiple mutations yield substantial enhancements of reactivation rates. Binary combinations of oximes and these mutant enzymes may form effective scavenging agents. (Supported by GM18360, DAMD1718014 and a fellowship of the Ministry of Science and Technology of the Republic of Croatia).

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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