Glutathione S-transferases of mouse liver: sex-related differences in the expression of various isozymes

Abstract

Sex-related differences in the expression of glutathione S-transferase (GST) isozymes of mouse liver have been described. There were no apparent qualitative differences in the isoelectric focusing profiles of the GST isozymes from male and female mouse liver. Both male and female mice have at least four GST isozymes in their liver with p I values of 9.8, 8.7, 6.4 and 5.7. Kinetic, immunological, and structural properties including the N-terminal region amino acid sequences of these isozymes have been determined and they have been classified into α, μ, and π classes. The most cationic isozyme (p I 9.8) belongs to the α class and is comparatively more abundant in female liver. The isozyme having p I 8.7 belongs to the π class and is more abundant in male liver. The μ class GST p I 6.4 as well as the isozyme having p I 5.7 which corresponded to the a class isozyme GST 8-8 of rat liver were more abundant (about 1.5-fold) in male mouse liver as compared to the female. Interestingly, present studies reveal sex-related differences in the heat stabilities of the α and π class GSTs of mouse liver. The α class GST p I (9.8) isolated from female mouse liver was more thermostable as compared to the corresponding enzyme from male mouse liver. On the contrary, the π class GST (p I 8.7) from male mouse was more thermostable as compared to the corresponding enzyme from the female mouse.