The systematic name of this enzyme class is purine-nucleoside:phosphate ribosyltransferase.

PNP metabolizes inosine into hypoxanthine and guanosine into guanine, in each case creating ribose phosphate.

Often the de novo pathway is interrupted as a result of chemotherapy drugs such as methotrexate or aminopterin.

All salvage pathway enzymes require a high energy phosphate donor such as ATP or PRPP.

[4] PNPase, together with adenosine deaminase (ADA), serves a key role in purine catabolism, referred to as the salvage pathway.