engleski

Mechanism of oxime reactivation of phosphorylated acetylcholinesterase analyzed by chirality and mutagenesis

We have examined the reactivation of a series of resolved enantiomeric methylphosphonate conjugates of acetylcholinesterase by two oximes, 2-PAM and HI-6. The rates of oxime reactivation show an Sp versus Rp preferance, similar to that found as previously for inactivation. A comparison of Sp and Rp-cycloheptyl-, 3,3-dimethylbutyl- and isopropyl methylphosphonyl conjugates shows that steric hidrance by the alkoxy group precludes facile access of the oxime to the tetraedral phosphorus. To facilitate access, we substituted smaller side chains in the acyl pocket and choline binding site of the enzyme. Phe295Leu and Phe297Ile acyl pocket substitutions enhance respectively HI-6 and 2-PAM elicited reactivation rates of the Sp conjugates, while in choline binding site Tyr337Ala enhance reactivation rates of both, Sp and Rp, conjugates.

acetylcholinesterase; organophosphates; reactivation; oximes; chirality

nije evidentirano