SULFUR OXYACID PRODUCTION AS A CONSEQUENCE OF PARATHION DESULFURATION

Parathion desulfuration in vitro by the rat liver microsomal oxidase system gives rise to reactive sulfur atoms which either covalently bind to microsomal macromolecules, most likely as hydrodisulfides (-SSH) or appear as water-soluble metabolites. The latter were tentatively identified as sulfate, thiosulfate, and a minor amount of sulfite. Production of sulfate was enhanced by glutathione. Moreover, glutathione and other thiols removed covalently bound sulfur from the microsomal membranes and partially restored activity to enzymes known to be inactivated during parathion metabolism. A semilogarithmic plot of sulfur removal with time indicated at least two populations of covalently bound sulfur differing in the stability of the hydrodisulfide bond or accessibility to thiol compounds. The significance of transient hydrodisulfide formation with regard to the production of sulfur oxyacids is discussed. Both macromolecular and low molecular weight endogenous sulfhy dryl-containing biochemicals may play a role in preventing sulfur binding in vivo since only low level sulfur binding in liver homogenates was observed after the in vivo administration of parathion. © 1979.