Properties of pig brain glutathione-S-transferase

Glutathione-S-transferase (GST) inactivates toxic electrophilic compounds, binding them to reduced glutathione. As has been demonstrated in the present paper, GST is a common enzyme in the porcine central nervous system. Its activity for the electrophilic substrate (1-chloro-2.4-dinitrobenzene) and the organic peroxide (cumene peroxide) was determined in all regions of the brain cortex, in white matter, hippocampus, brain stem and cerebellum. Two isoforms of a molecular mass of approximately 40 kD were identified in each region of the brain. The isoforms showed different electrical charges, isoelectric points and substrate affinities. The main isoform, contained about 90% of the total activity: its pI was 7.2. The remaining 10% of the activity were expressed by the isoform with pI 6.5. This isoform demonstrated twice the affinity for reduced glutathione and for electrophilic substrate than the major isoform pI 7.2. The presence of two isoforms in all the studied regions of the brain indicates that glutathine-S-transferases play an important role in protecting the central nervous system against toxic electrophiles.