Active site mutant acetylcholinesterase interactions with 2-PAM, HI-6, and DDVP.
We used mouse recombinant wild-type acetylcholinesterase (AChE; EC 3.1.1.7), butyrylcholinesterase (BChE; EC 3.1.1.8), and AChE mutants with mutations (Y337A, F295L, F297I, Y72N, Y124Q, and W286A) that resemble residues found at structurally equivalent positions in BChE, to find the basis for divergence between AChE and BChE in following reactions: reversible inhibition by two oximes, progressive inhibition by the organophosphorus compound DDVP, and oxime-assisted reactivation of the phosphorylated enzymes. The inhibition enzyme-oxime dissociation constants of AChE w.t. were 150 and 46 microM, of BChE 340 and 27 microM for 2-PAM and HI-6, respectively. Introduced mutations lowered oxime binding affinities for both oximes. DDVP progressively inhibited cholinesterases yielding symmetrical dimethylphosphorylated enzyme conjugates at rates between 104 and 105/min/M. A high extent of oxime-assisted reactivation of all conjugates was achieved, but rates by both oximes were up to 10 times slower for phosphorylated mutants than for AChE w.t.
Kovarik
Zrinka
Z
Institute for Medical Research and Occupational Health, Ksaverska c. 2, POB 291, HR-10001 Zagreb, Croatia. zrinka.kovarik@imi.hr
Ciban
Nikolina
N
Radić
Zoran
Z
Simeon-Rudolf
Vera
V
Taylor
Palmer
P
D000110:Acetylcholinesterase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D004006:Dichlorvos / Q000737:chemistry / Q000378:metabolism*; D004347:Drug Interactions; D051379:Mice; D009154:Mutation / Q000235:genetics*; D010091:Oximes; D011220:Pralidoxime Compounds / Q000737:chemistry / Q000378:metabolism*; D011726:Pyridinium Compounds / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins
D010091:Oximes; D011220:Pralidoxime Compounds; D011726:Pyridinium Compounds; D011994:Recombinant Proteins; D004006:Dichlorvos; D000110:Acetylcholinesterase; C022870:asoxime chloride