FIGURE 6.

Competition between CBA and FOX reagent for TyrOOH generated in XO/HRP system. Reaction mixtures containing tyrosine (1 mm), hypoxanthine (1 mm), catalase (0.25 kilounits/ml), HRP (0.5 units/ml), XO (2.8 milliunits/ml), phosphate buffer (50 mm, pH 7.4), DTPA (0.1 mm), and SOD (0.1 mg/ml, where indicated) were incubated for 1 h, after which SOD was added to all samples to stop the production of TyrOOH. Next, CBA (final concentration, 0.1 mm) or FOX or both reagents were added (see “Results”). Open symbols are related to absorbance scale (left axis); solid symbols are related to fluorescence scale (right axis). Error bars, S.D.