Glutathione S-transferases of human skin: qualitative and quantitative differences in men and women

Glutathione S-transferase (GST) isozymes of male and female leg skin have been characterized. GST activities and protein have been quantified in a number of male and female skin samples and the results indicate that as compared to the male skin, female skin contains a higher amount of GST activity as well as protein. Both male and female leg skin contain three GST isozymes with pI values 9.9, 9.1 and 4.8. In accordance with previous findings the major isozyme, pI 4.8 belongs to the pi-class, whereas the two minor forms pI 9.1 and 9.9 belong to the alpha-class. Each of the three isozymes is more abundant in female skin. Surprisingly, the specific activities and Kcat values of the female skin GSTs, particularly of the pi-class isozyme were found to be significantly higher as compared to those of male skin isozyme. Studies into the kinetics of inhibition by hematin also indicated differences in male and female skin GSTs. Whereas we confirm the presence of an alpha-class GST, pI 9.9, in human skin with an apparently higher subunit M(r) value as compared to other human alpha-class GSTs, contrary to the previous report (Del Boccio et al. (1987) Biochem. J. 244, 21-25), the results of the present studies show that the N-terminus of this alpha-class GST is blocked.