Purine nucleoside phosphorylase (also known as PNPase) is an enzyme (EC 2.4.2.1) 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.https://www.creative-enzymes.com/product/Native-Bacillus-Sp-Purine-Nucleoside-Phosphorylase_760.html