Hydrolytic Detoxification of Sarin Analogues by Aminopeptidase P (AMPP)
Date Issued
2005
Date
2005
Author(s)
Su, Chiao-Yung
DOI
zh-TW
Abstract
Previous catalytic studies have shown that the aminopeptidase P (AMPP) from Escherichia coli catalyzes the hydrolysis of a variety of organophosphate triesters, which includes an array of insecticides. Herein we report another novel activity of AMPP to degrade methylphosphonates (sarin analogues) and ethylphosphonates. A series of racemic mixtures of methylphosphonates and ethylphosphonates containing various combinations of methyl, ethyl, i-propyl, n-propyl, sec-butyl, and phenyl substitutes were prepared as probes of the structural constraints within the active site of AMPP. This result demonstrates that wild type AMPP favors the hydrolysis of compound 4, O-methyl p-nitrophenyl methylphosphonate. At a concentration of 500 μM compound 4 is hydrolyzed 7- to 15-fold faster than are the corresponding analogues (5-9). Enzymatic hydrolysis of O,O-diisopropyl-p-nitrophenyl phosphate (20) in H218O observed 18O-labeled O,O-diisopropyl phosphate product only and confirmed that the catalytic reaction took place with cleavage of P-O bond. From chemical and kinetic studies, the utilization of a optically pure Sp-10 has demonstrated that the enzymatic reaction proceeds via an SN2-like mechanism and in situ generates a chiral product with an inversion of stereochemical configuration at the phosphorus atom. The results finally conclude that enlargement of the active site through the site-directed mutagenesis does result in a preference toward the Sp-isomer of O-methyl p-nitrophenyl methylphosphonothioate(Sp-10).
Subjects
解毒
沙林
水解
微波
酵素
detoxification
sarin
hydrolysis
microwave
enzyme
Type
thesis