PURIFICATION AND CHARACTERIZATION OF GLUTATHIONE S-TRANSFERASES OF RAT UTERUS

Glutathione S-transferases (GSTs) provide protection to cells against electrophilic xenobiotics as well as lipid hydroperoxides and 4-hydrox ynonenal generated during lipid peroxidation. The catalytic properties of the alpha class GSTs are web suited for detoxification of electrop hilic products of lipid peroxidation. An immunologically distinct subg roup of the at class CST isozymes having high activity towards 4-hydro xynonenal has been recently identified in several mammalian tissues [Z imniak ei al. (1994) J. Biol. Chem. 269, 992-1000]. Since oxidative st ress can exert deleterious effects during gestation, the present studi es were performed to determine whether the rat homolog of this group o f GSTs, rGST 8-8, is expressed in gravid rat uterus, where it may func tion as a defense mechanism against oxidative stress. GSTs were purifi ed by GSH-affinity chromatography. Individual GST isozymes were separa ted by column isoelectric focusing and their immunologic identities we re established using highly specific polyclonal antibodies in Western blot analysis. Their expression was quantified and kinetic properties were characterized. Rat uterus contained an alpha class GST (pI 9.8), a pi class GST (pI 8.1), two mu class GSTs (pI 6.7 and 6.2) and rGST 8 -8. This result indicated that rGST subunits 1, 2, 3, 4, 7 and 8 are p resent in rat uterus. The relative abundance of rGST 8-8 in the gravid rat uterus was found to be about three-fold higher as compared with t hat previously seen in rat liver. Higher relative abundance of rGST8-8 in gravid rat uterus suggests that it may play a protective role agai nst the deleterious effects of lipid peroxidation during gestation. Co pyright (C) 1996 Elsevier Science Ltd