Purine nucleoside phosphorylase (PNP) (E.C. 2.4.2.1.) is an enzyme involved in purine metabolism and it catalyzes the cleavage of the glycosidic bond of ribo- or deoxyribonucleosides, in the presence of inorganic phosphate as a second substrate, to generate the purine base and ribose-1-phosphate or deoxyribose-1-phosphate. It is one of the enzymes of the nucleotide salvage pathways that allow the cell to produce nucleotide monophosphates when the de novo synthesis pathway has been interrupted or is non-existent (as is the case in the brain). PNP is a cytosolic enzyme.

Suitable for the detection of Purine Nucleoside Phosphorylase activity in cell and tissue lysate or purified recombinant protein.

In this Purine Nucleoside Phosphorylase Activity Assay, hypoxanthine formed by the breakdown of inosine is further converted to uric acid using a developer. The uric acid is measured at a wavelength of 293 nm. Limit of quantification is 0.1μU recombinant purine nucleoside phosphorylase.