Induction and development of mouse liver glutathione S-transferase activity

Glutathione S-transferase in humans: development and tissue distribution

Glutathione S-transferase (GST) was investigated with benzo(a)pyrene-4,5-oxide (BPO) as substrate in tissue specimens from 26 fetal and 27 adult livers and 27 placentas. The average (+/- SEM) of GST activity in the cytosol was 1.80 +/- 0.18 (fetal liver), 3.05 +/- 0.30 (adult liver) and 1.18 +/- 0.07 (placenta) nmol/min/mg. GST was also investigated in human fetal and adult lungs, kidneys and gut. In these tissues the average (+/- SEM) GST activity ranged between 0.71 +/- 0.12 (adult intestine) and 2.11 +/- 0.18 (fetal lungs) nmol/min/mg. Whereas in the fetal liver the conjugation of BPO was catalyzed at a rate of about two-thirds of the adult rate, similar or higher GST activities were found in the fetal non-hepatic tissues as compared to the adult organs. No correlation was found between the activity of the GST in fetal liver and placenta and the gestational age (11-25 weeks). GST develops before the 11th week of gestation and it does not undergo changes during the mid-gestation. No correlation was found between GST activity in adult liver and age (32-70 years).

Glutathione transferases in aquatic and terrestrial animals from nine phyla

Glutathione transferase (GST) was present in 71 of 72 animal species/stages representing nine phyla when measured with 1-chloro-2,4-dinitrobenzene (CDNB). Our hypothesis that all animals have GST was not falsified. Transferase activity towards ethacrynic acid (ETHA) was present in species from all phyla investigated, but some animals seem to be without this activity. Activity towards 1,2-dichloro-4-nitrobenzene (DCNB) was less developed in aquatic animals than in terrestrial ones. The amount of protein binding to GSH-affinity gel matrix was rather uniform, ranging between 0.3 and 0.7% of soluble protein in homogenates of widely diverse animal species, thus being less variable than the enzyme activity. Transferases active towards DCNB did not bind at all or were less firmly bound to the GSH-affinity gel than the activity towards CDNB or ETHA. Fractionation was obtained by using a gradient of GSH. With SDS-electrophoresis it was demonstrated that the proteins with affinity to GSH had monomers in the MW-range 21.500-29.000. Hydra attenuata had one band (MW = 25,000); all other sources gave a complex pattern with up to six bands. It is concluded that GSTs are characteristic major constituents of animal cells, probably with some common basic function. Mutant forms able to aid detoxication are retained in the phylogenesis when they increase the fitness of the animal.

Isoelectric focusing of brain cortex GSH S-transferase activity in mammals: evidence that polymorphism is absent in man

Specific activities of GSH S-transferase toward different model substrates were determined in the cytosol prepared from rat, guinea pig, rabbit, mouse, sheep, beef, pig and human brain cortex. The GSH S-transferase composition of the eight mammalian brain cortices was studied by using density gradient isoelectric focusing technique. Human brain cortex GSH S-transferase was resolved into a single peak of activity centered at pH 4.6, whereas the supernatants of all other mammals consisted of more than one enzymatic form. The kinetic properties of all forms isolated were compared.

Endogenous induction of epoxide hydrolase, benzo(a)pyrene hydroxylase and glutathione-S-transferase in "responsive" C57Bl/6 mice and in "nonresponsive" DBA/2 mice during pregnancy

Gestational changes in activity for three enzymes associated with different hepatic and pulmonary drug metabolizing systems were investigated in C57Bl/6 and DBA/2 mice: benzo(a)pyrene hydroxylase, epoxide hydrolase and glutathione-S-transferase. The gestational profiles of hepatic and pulmonary benzo(a)pyrene hydrolase, and epoxide hydrolase were similar in both strains. In addition, we demonstrated higher endogenous stimulation of the three studied enzymic activities in C57Bl/6 mice. During the second moiety of pregnancy, temporal variations were observed: a peak of activity occurred between days 17 and 18 for lung and liver benzo(a)pyrene hydroxylase and at day 20 for epoxide hydrolase in both strains. Hepatic glutathione-S-transferase variations were similar in both strains. However, pulmonary glutathione-S-transferase increased gradually throughout pregnancy in C57Bl/6 mice, while a peak of glutathione-S-transferase activity occurred on day 18 of gestation in DBA/2 mice.

Glutathione peroxidase, glutathione reductase, glutathione S-transferase, and gamma-glutamyltranspeptidase activities in the human early pregnancy placenta

GSH peroxidase, GSSG reductase, GSH S-transferase, and gamma-glutamyltranspeptidase activities were measured in the supernatant of 13 human early pregnancy placenta homogenates. From measurements of GSH peroxidase activity with both H2O2 and cumene hydroperoxide as second substrate it was deduced that immature placenta contains only the Se-dependent form. All the specimens investigated exhibited GSSG reductase and gamma-glutamyltranspeptidase activities. GSH S-transferase activity was noted only using 1-chloro-2,4-dinitrobenzene as electrophilic substrate, while no detectable activity was found with 1,2-dichloro-4-nitrobenzene, 1,2-epoxy-3-(p-nitrophenoxy) propane, and p-nitrobenzylchloride. It is concluded that human placenta is equipped, from early pregnancy, with the enzymatic systems which are involved in GSH-mediated cellular detoxication and in preserving the integrity of the sulfhydryl status of the cells.

Studies on the induction of glutathione S-transferases in mouse liver

The induction of glutathione S-transferase activity by phenobarbital was studied in the male mouse. Ion-exchange chromatography and density gradient isoelectric focusing were used to characterize the induction. Two transferases were separated by column chromatography, one peak was induced by phenobarbital while the other peak was unaffected. Three peaks of transferase activity were observed when control or induced cytosol was applied and eluted from a density gradient isoelectric focusing column. The induced F2 peak had twice the activity of the F2 control. The amount of activity in the peak labeled F3 was unaltered with PB treatment. It appears that at least one transferase is more inducible by phenobarbital than the others.