GLUTATHIONE S-EPOXIDETRANSFERASE IN THE HUMAN-PLACENTA AT DIFFERENT STAGES OF PREGNANCY

  • 1 January 1981
    • journal article
    • research article
    • Vol. 9  (5) , 472-475
Abstract
Glutathione S-transferase activity with styrene 7,8-oxide as substrate was studied in the soluble fraction of human placentas. Measurable enzyme activities were noted in all placental specimens studied. The mean activity was 5.61 .+-. 0.59 (SE) nmol of conjugate formed per min per mg of microsomal protein in midgestational placentas obtained between the 8th-25th wk of gestation. The corresponding activity was only 2.07 .+-. 0.34 (SE) in 4 term placental specimens. No relation between the enzyme activities and the smoking habits of the women was observed. Linear kinetics of the enzyme were observed with respect to styrene 7,8-oxide and glutathione as substrates. Placental tissue catalyzes not only the formation of previously demonstrated reactive metabolites but also the further metabolism of such metabolites via conjugation with glutathione. The clinical significance of these findings is unclear but the balance between the placental formation of toxic metabolites and their further degradation may be important in regulation of the quantities of such metabolites that reach the fetal compartment.