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Download fileCharacterization of a Phosphodiesterase Capable of Hydrolyzing EA 2192, the Most Toxic Degradation Product of the Nerve Agent VX†
journal contribution
posted on 07.08.2007, 00:00 authored by Eman Ghanem, Yingchun Li, Chengfu Xu, Frank M. RaushelGlycerophosphodiesterase (GpdQ) from Enterobacter aerogenes is a nonspecific diesterase
that enables Escherichia coli to utilize alkyl phosphodiesters, such as diethyl phosphate, as the sole
phosphorus source. The catalytic properties of GpdQ were determined, and the best substrate found was
bis(p-nitrophenyl) phosphate with a kcat/Km value of 6.7 × 103 M-1 s-1. In addition, the E. aerogenes
diesterase was tested as a catalyst for the hydrolysis of a series of phosphonate monoesters which are the
hydrolysis products of the highly toxic organophosphonate nerve agents sarin, soman, GF, VX, and rVX.
Among the phosphonate monoesters tested, the hydrolysis product of rVX, isobutyl methyl phosphonate,
was the best substrate with a kcat/Km value of 33 M-1 s-1. The ability of GpdQ to hydrolyze the phosphonate
monoesters provides an alternative selection strategy in the search of enhanced variants of the bacterial
phosphotriesterase (PTE) for the hydrolysis of organophosphonate nerve agents. This investigation
demonstrated that the previously reported activity of GpdQ toward the hydrolysis of methyl demeton-S
is due to the presence of a diester contaminant in the commercial material. Furthermore, it was shown
that GpdQ is capable of hydrolyzing a close analogue of EA 2192, the most toxic and persistent degradation
product of the nerve agent VX.