PNP Assay Kit provides an enzymatic tool allowing direct continuous spectrophotometric monitoring of PNP activity in a convenient 96-well plate format. In the assay, PNP activity is measured as a rate of production of hypoxanthine, which is directly oxidized by XDH enzyme with concomitant reduction of NAD+ to NADH measurable by absorbance at 340nm.
The assay is developed for measuring PNP activity in vitro or in cell lysates.
For maximal accuracy, the assays with cell lysates are run with and without inosine in parallel. The absorbance rate observed in the absence of inosine is used as blank and is subtracted from the absorbance rate measured in its presence.