Microsomal glutathione S-transferase (GST) isozymes in Aspergillus ochraceus TS: induction by 3-methylcholanthrene

Induction of microsomal glutathione S-transferase isozymes in Aspergillus ochraceus TS is reported. Among the inducers of mammalian drug-metabolising enzymes 3-methylcholanthrene, benzo(a)pyrene and polychlorinated biphenyl enhanced the microsomal GST activity quite considerably. On the other hand phenobarbital, beta-naphthoflavone and trans-stilbene oxide were almost without any effect. To our knowledge this seems to be the first report on induction of microsomal GST in lower eukaryotes. A significant increase (7.9 fold) in GST activity was observed with the cells induced by 3-methylcholanthrene. Moreover, three new GST isozymes were found to be present in 3-methylcholanthrene induced microsomes. The isozymes are basic in nature. The GST isozymes were found to be catalytically distinct from each other.