Purine nucleoside phosphorylase (also known as PNPase) is an enzyme (EC 126.96.36.199) involved in purine metabolism. PNP metabolizes adenosine into adenine, inosine into hypoxanthine, and guanosine into guanine, in each case creating ribose phosphate. NP encodes the enzyme purine nucleoside phosphorylase that together with adenosine deaminase (ADA) serves a key role in purine catabolism, referred to as the salvage pathway. Mutations in either enzyme result in a severe combined immunodeficiency (SCID). Confusingly, the same abbreviation (PNPase), is also used for another, otherwise unrelated, enzyme, namely Polynucleotide Phosphorylase.
PNPase (Bacillus sp.)
PNPase; PUNPI; PUNPII
Useful for enzymatic determination of inorganic phosphate
Colourless to light brown solution
Purine Nucleoside Phosphorylase produced in microorganism has a molecular mass of 32 kDa.
Enzyme Commission Number
NADH oxidase < 0.002%
6.0-10.0 (37°C (Tris-HCI buffer)
Stable at 65°C and below (pH 8.5, 10 mins)
Nicotinate and nicotinamide metabolism; Purine metabolism; Pyrimidine metabolism; Nucleotide metabolism.
purine-nucleoside phosphorylase activity; purine-nucleoside phosphorylase activity; purine-nucleoside phosphorylase activity.
inosine phosphorylase; PNPase; PUNPI; PUNPII; inosine-guanosine phosphorylase; nucleotide phosphatase; purine deoxynucleoside phosphorylase; purine deoxyribonucleoside phosphorylase; purine nucleoside phosphorylase; purine ribonucleoside phosphorylase; purine-nucleoside: phosphate ribosyltransferase; EC 188.8.131.52