Resolution, purification and some properties of three glutathione transferases from rat liver mitochondria

From the matrix of rat liver mitochondria, three GSH transferases were isolated and named Transferase 1, 2.1 and 2.2. Transferases 1 and 2.2 were purified to electrophoretic homogeneity. Transferase 1 contributes up to about 90% of the total mitochondrial GSH-transferring activity. It has a molecular weight of approx. 45 000 and is composed of two subunits of similar size. The isoelectric point is at pH 7.1-7.4. The Km values for GSH and 1-chloro-2,4-dinitrobenzene are 0.3 and 0.7 mmol/l respectively. Transferase 2.2 has the same molecular weight and subunit structure like the Transferase 1 and an isoelectric point at pH 4.8. The apparent Km values for GSH and 1-chloro-2,4-dinitrobenzene are 0.3 mmol/l and 0.4 mmol/l respectively. Transferase 2.1 contributes only 1% of the total mitochondrial GSH-transferring activity. It has high apparent Km values for both GSH and 1-chloro-2,4-dinitrobenzene (5.6 mmol/l and 1.3 mmol/l resp.) and a limited spectrum of substrates.