FIGURE 2.

Formation of hydroperoxides during oxidation of urate by LPO in the presence of superoxide. For the complete system, urate (200 μm) was incubated with LPO (150 nm) and xanthine oxidase (XO, 200 nm) in 50 mm phosphate buffer, pH 7.4. Reactions were started by the addition of acetaldehyde (Acet, 3 mm) to produce a superoxide flux of 6 μm/min and stopped after 30 min by adding catalase (100 μg/ml). Hydroperoxides were quantified by the FOX assay and were expressed as hydrogen peroxide equivalents. When added to the reaction system, catalase (Cat) and superoxide dismutase (SOD) were present at 100 and 20 μg/ml, respectively. Data are means and ranges of at least duplicate experiments.