Figure 2.

SIN-1 activation of GSH-Px/GSH inhibited PGH synthase-1. The assay conditions were identical to those described in the legend to Fig. 1 except that SIN-1 (750 μM) was added instead of peroxynitrite. Control PGH synthase-1 activity in the absence of GSH-Px was 1155 and 813 pmol product/pmol PGH synthase-1 at 0.25 and 2.5 mM GSH, respectively. □, 0.25 mM GSH; ▪, 1.0 mM GSH; ▵, 2.5 mM GSH; •, 0.25 mM GSH plus 1 μM SOD. The rate of formation of peroxynitrite from 750 μM SIN-1 in 0.1 M NaPO₄ (pH 8.0) containing 500 μM phenol was estimated to be 30 μM/min following a 60-sec lag by monitoring the rate of oxygen uptake.