Guanosine phosphorylase

In enzymology, a guanosine phosphorylase (EC 2.4.2.15) is an enzyme that catalyzes the chemical reaction

Thus, the two substrates of this enzyme are guanosine and phosphate, whereas its two products are guanine and alpha-D-ribose 1-phosphate.

This enzyme belongs to the family of glycosyltransferases, specifically the pentosyltransferases. The systematic name of this enzyme class is guanosine:phosphate alpha-D-ribosyltransferase. This enzyme participates in purine metabolism.