PLANT BIOCHEMISTRY OF XENOBIOTICS - ISOLATION AND CHARACTERIZATION OFA SOYBEAN O-GLUCOSYLTRANSFERASE OF DDT METABOLISM

The insecticide DDT is metabolized in soybean and wheat cell cultures to the acylglucoside of 2,2-bis-(4-chlorophenyl)-acetic acid (DDA) (M. Arjmand and H. Sandermann, 1985, Pesticide Biochem. Physiol. 23, 389- 397). An enzyme catalyzing the conjugation reaction has been highly pu rified from the soluble enzyme fraction of cultured soybean cells. Aft er the initial ammonium sulfate fractionation, quercetin and pentachlo rophenol were preferentially glucosylated. In the course of 367-fold p urification, DDA became the preferred substrate. The purified enzyme w as unstable. A molecular weight of similar to 50 kDa was estimated for the native enzyme (gel permeation chromatography) as well as the dena tured protein (sodium dodecyl sulfate-gel electrophoresis). The isoele ctric point for the enzyme was near pH 4.9. Apparent K-m values of abo ut 170 mu M were determined for UDP-glucose as well as DDA. The maxima l velocity was 257 mu kat/kg protein, corresponding to a conjugation c apacity of 855 mu g DDA/h/g fresh weight of cells. (C) 1994 Academic P ress,Inc.