Purine Nucleoside Phosphorylase




This enzyme is useful for enzymatic determination of  inorganic phosphorus, 5′-nucleotidase and adenosine deaminase when coupled with xanthine oxidase and uricase.

Purine Nucleoside Phosphorylase


One unit (U) is defined as the amount of enzyme which produces 1 μmol of hypoxanthine per min under the conditions described below.


Reagent I: Add 0.0372 g EDTA·2Na, 0.07 g sodium cholate, 1mL 4-AA (50 mM) in 40 mL of 0.1 M pH 7.5 potassium phosphate buffer, adjust to pH 7.5, then add 200 U xanthine oxidase and set to 50 mL.

Reagent II: Add 0.161 g inosine, 9.5 mL TOOS (50 mM), 0.5 mL POD (1 kU/mL) to 0.1 M pH 7.7 potassium phosphate buffer, adjust to pH 7.7, then set to 50 mL.

Enzyme diluent: Add 0.0372 g EDTA·2Na and 0.07 g sodium cholate in 50 mL of 0.1M pH 7.5 potassium phosphate.

Sample: Dilute the sample to 0.2-0.3 U/mL by enzyme diluent.


  1. Add 0.75 mL of Reagent I, 0.15 mL of Reagent II to a cuvette and preincubate the reaction mixture at 37 ℃ for 5 min.
  1. Add 0.015 mL enzyme solution to the cuvette and mix.
  1. Record the ΔAs at 555 nm in 1 minute in a spectrophotometer thermo stated at 37 ℃.

At the same time, measure the blank rate ΔAb by using the same method as the test except that the enzyme diluent is added instead of the enzyme


∆A = ∆As – ∆Ab



  1. R.E. Parks, Jr. and R.P. Agarwal; The Enzymes, Vol.7, p483 (3rd ed.) (1972).
  1. P.A. Hoffe, R. May and B.C. Robertson; Methods in Enzymology, Vol.11, p70 (1972).
  1. M. Sugiura, K. Kato, T. Adachi, Y. Ito, K. Hirano and S. Sawaki; Chem. Pham. Bull., 29, 1451 (1981).
  1. P. Fossati; Analytical Biochemistry, 149, 62 (1985).