Adenosine Deaminase Assay
Method: The reaction velocity is measured by a change in absorbance at 265 nm resulting from the deamination of adenosine. One unit converts one micromole of adenosine to inosine per minute at 25°C and pH 7.4 under the specified conditions.
Dilute immediately before use in ice cold 0.05 M phosphate buffer, pH 7.4 to a concentration of 0.2 - 0.8 units / ml.
Adjust spectrophotometer to 265 nm and 25°C.
Pipette into cuvettes as follows:
Incubate in spectrophotometer for 3-5 minutes to achieve temperature equilibration and establish blank rate, if any. At zero time add 0.02 ml enzyme solution and mix thoroughly. Record decrease in A265 for 2-3 minutes. Use the initial rate to calculate ΔA265/min.