Levels and subcellular distributions of detoxifying enzymes in the ovarianCorpus luteum of the pregnant and non-pregnant pig

The levels and subcellular distribution of enzymes involved in defenses aga inst reactive oxygen superoxide dismutase (SOD; E.C.1.15.1.1), glutathione peroxidase (GPX; E.C.1.11.1.9), catalase (CAT; E.C.1.11.1.6), and DT-diapho rase (DT; E.C.1.6.99.2) and of the conjugating enzymes glutathione transfer ase (GST; E.C.2.5.1.18) and p-sulphotransferase (p-ST; E.C.2.8.2.1) in the corpus luteum of ovaries from pregnant and non-pregnant pigs were investiga ted. In addition, non-protein thiols and glutathione reductase (GRD; E.C.1. 6.4.2) were examined in the same manner. The total cytosolic activities of CAT, DT, GRD, and p-ST were significantly increased, whereas total GST acti vity was decreased in the pregnant corpus luteum compared to the correspond ing activities in non-pregnant corpus luteum. In the case of the mitochondr ial fraction from pregnant corpus luteum, GPX and GRD displayed significant increases in specific activity. Upon subfractionation of the mitochondrial fraction (i.e. mitoplast preparation), SOD activity was distributed equall y between the mitoplasts and the supernatant. CAT and GPX activities were m ainly recovered in the supernatant, while the major GRD activity pelleted w ith the mitoplasts. Microsomes from pregnant corpus luteum demonstrated inc reased specific GPX activity and decreased SOD activity compared to the non -pregnant corpus luteum. No differences in the non-protein thiol levels in the cytosolic, mitochondrial, or microsomal fractions from the corpus luteu m were observed between non pregnant and pregnant sows. (C) 1999 Elsevier S cience Inc.