Glutathione conjugation plant enzymes

Propachlor Is metabolized by this route In both a resistant and a susceptible species (Equation 16). Glutathione conjugation of propachlor occurs very rapidly Un vitro in the absence of GST enzymes (78) and It Is not clear whether differences In GSH and/or GST concentratlois influence the selectivity of propachlor and related herbicides. The concentration of GSH In higher plants Is estimated... 

Glutathione S-transferase enzymes have been detected In a variety of different plant species (24,76.64.97.101.107-110). Howevei, detailed enzyme studies have been limited to corn (24.76, J09., 12 ) and pea (. JOT., 110). The foliar tissue of corn contains a GST Isozyme that appears rather unique In Its ability to catalyze the conjugation of various 2-chloro-s-trlazlnes with GSH (78). The molecular weight and other properties of this Isozyme are similar to those reported for many mammalian GST Isozymes however, the pH optimum of this Isozyme for atrazine Is somewhat lower than that reported for many GST Isozymes (, 78,J09.). When corn Is treated with R-25788, a second Isozyme Is Induced ( ). The Induced Isozyme Is very effective In catalyzing the GSH conjugation of an a-chloroacetamlde herbicide (alachlor), but It was not assayed with atrazine ( ). 

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