Note: Prior to use, the 0.1 M sodium borate buffer and the 0.12 mM uric acid solution should be oxygenated by bubbling O2 through the solutions for 10-15 minutes. Reoxygenate every 20 minutes.
Dissolve at one mg/ml in cold (5°C) 0.1 M sodium borate buffer, pH 8.5.
Immediately prior to assay, dilute further to a concentration of 0.01-0.1 units/ml.
Adjust the spectrophotometer to 290 nm and 25°C.
Pipette into a cuvette as follows:
Borate buffer 0.5 ml 0.12 mM Uric acid 2.0 ml
Incubate in spectrophotometer for 4-5 minutes to achieve temperature equilibration and to establish blank rate, if any. At zero time add 0.5 ml of enzyme and record decrease in A290 for 6-7 minutes. Calculate ΔA290 from initial linear portion of curve.
