Background: The glutathione S-transferases (GSTs) are family of enzymes that are notable for their
role in phase II detoxification reactions. Antibiotics have been reported to have several adverse effects on the
activity of the enzymes in mammals.
Aim: The aim of this study was the structural and biochemical characterization of rat erythrocyte GST and understanding
the effects of gentamicin, clindamycin, cefazolin, ampicillin and scopolamine butylbromide on the
activity of human erythrocyte GST using rat as a model.
Methods: The enzyme was purified by GSH-agarose affinity chromatography. In vitro GST enzyme activity
was measured at 25°C using CDNB as a model substrate. IC50 of drugs was measured by activity % vs compound
concentration graphs. Lineweaver Burk graphs were drawn to determine the inhibition type and Ki constants
for the drugs. The structure of the enzyme was predicted via Protein Homology/analogy Recognition Engine.
Results: In this study, GST was purified from rat erythrocyte with a specific activity of 6.3 EU/mg protein, 44
% yield and 115 fold. Gentamicin and clindamycin inhibited the enzymatic activity with IC50 of 1.69 and 6.9
mM and Ki of 1.70 and 2.36 mM, respectively. Ampicillin and scopolamine butylbromide were activators of
the enzyme, while the activity of the enzyme was insensitive to cefazolin. The enzyme was further characterized
by homology modeling and sequence alignment revealing similarities with human GST.
Conclusion: Collectively, it could be concluded that gentamicin and clindamycin are the inhibitors of erythrocyte