FIGURE 1.

Identification of the product formed from the reaction between CBA and TyrOOH. Insets show the online absorption spectra collected by a diode array detector for the eluted analytes. TyrOOH was generated in the reaction mixture containing tyrosine (1 mm), hypoxanthine (0.5 mm), catalase (0.25 kilounits/ml), HRP (2 μg/ml), XO (0.6 milliunits/ml), phosphate buffer (50 mm, pH 7.4), and DTPA (0.1 mm) with and without allopurinol (0.3 mm), as indicated. After 1 h of incubation, the reaction was stopped by the addition of allopurinol to the allopurinol-free sample, and CBA (0.1 mm) was added to both samples. The concentration of CBA and COH standards was 0.1 mm.