Compartmentation of the plant metabolic enzymes for the persistent plasticizer chemical,bis-2(-ethylhexyl)-phthalate

The environmentally persistent plasticizer chemical, bis-(2-ethylhexyl)-phthalate (DEHP), was not translocated or metabolized over 17 days after application to intact wheat leaves. The chemical was specifically associated with the cuticle fraction. In contrast, metabolism was observed in injured leaves and in leaf homogenates.DEHP esterase was 10-fold purified from the wheat leaf homogenate, and an apparent molecular weight of 38 000 was determined by gel permeation chromatography.Cleavage of DEHP by the partially purified esterase was strongly inhibited by a wheat cell wall and by a triglyceride preparation. Cleavage of the water-soluble substrate, 4-nitrophenylacetate, was not inhibited under the same conditions.Compartmentation of metabolic enzymes is proposed as an explanation for the persistence of DEHP and certain other environmental chemicals in plants.