Measurement of glutathione requiring enzymes involved in arachidonic acid cascade of rat basophilic leukemia cells.

Rat basophilic leukemia cells have frequently been employed for investigating the pathways of leukotriene biosynthesis, a class of biologically active arachidonic acid metabolites. However, information is lacking on the levels of selenium-dependent glutathione peroxidase (Se-GSH-Px), non-Se-GSH-Px and glutathione S-transferases (GSH-S-Trs), key enzymes involved in fatty acid hydroperoxide metabolism and leukotriene biosynthesis in these cells. Both GSH-S-Trs and non-Se-GSH-Px reactions are catalyzed by the same enzyme. In the present studies, we have measured the enzyme activities of GSH-Px(s) and GSH-S-Trs in the 105,000 X g supernatant fraction of sonified RBL-1 cells. The specific activities for GSH-Px(s) toward H2O2, cumene hydroperoxide, and 15S-hydroperoxy-eicosatetraenoic acid (15S-HPETE) are 12.6, 17.9 and 26.9 nmoles X min-1 X mg-1 protein, respectively. A specific activity of 18.9 nmoles X min-1 X mg-1 protein with 1-chloro-2,4-dinitrobenzene was estimated for the GSH-S-Trs. Therefore, the cell fraction that exhibits 5-lipoxygenase activity also contains selenium and non-selenium glutathione peroxidases.