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.


  • 1.4 mM Adenosine in 0.05 M Phosphate buffer, pH 7.4
  • 0.05 M Phosphate buffer, pH 7.4


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:

0.05 M Phosphate buffer, pH 7.4 2.88 ml
1.4 mM Adenosine 0.1 ml

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.



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