Nature of a Soluble, Glutathione-Dependent Enzyme System Active in Cleavage of Methyl Parathion to Desmethyl Parathion

Blood Cholinesterases as Human Biomarkers of Organophosphorus Pesticide Exposure

“…Glutathione transferases (postmicrosomal fraction of liver) catalyze the transfer ofO-alkyl and 0-aryl groups to glutathione. Reactions involving dimethyl-substituted phosphate and phosphorothioate esters such as dichlorvos, methyl paraoxon, methyl parathion, fenitrothion, and azinphosmethyl have been reported (Hollingworth 1970(Hollingworth , 1971Fukami and Shishido 1966;Fukunaga et al 1969). 0-alkyl transfers yield S-methyl glutathione and monodesmethyl products.…”

Glutathione S-Transferases of Rat Liver Active on Organophosphorus Triesters

“…36,000). It has been documented that some organophosphorus triesters as methyl parathion, parathion and diazinon conjugate with GSH at two positions of the molecule; O-alkyl portion 7 ) and O-p-nitrophenyIB) or O-pyrimidinyl moiety.6,9) However, it was not defined whether these two modes of reaction were catalyzed by the same enzyme or by different enzymes.…”

The metabolism and degradation of vinyl phosphate insecticides

“…Cis-mevinphos is O-desmethylated by a glutathione-dependent soluble enzyme (cf. FUKAMI andSmsmoo 1966, HUTSON et al 1972), whilst trans-mevinphos undergoes hydrolysis at the P-O-vinyl bond eatalysed by an enzyme whieh does not require glutathione as eofactor, thus illustrating an interesting differenee in the detoxmcation pathways for two geometrie isomers. It is unlikely that there is absolute stereospecificity, but rather that the rapid esterase-catalysed hydrolysis of the trans-isomer prevents its degradation by the glutathione-dependent system.…”