cellulomonas sp. Purine Nucleoside Phosphorylase (PNP)

The ubiquitous enzyme purine nucleoside phosphorylase (PNP, E.C. 2.4.2.1.) catalyzes the reversible phosphorolysis of naturally occurring purine nucleosides, and many analogues, as follows: $$\beta {\rm{ - purine}}\,{\rm{nucleoside}}\,{\rm{ + }}\,{\rm{orthophosphate}}\, \Leftrightarrow \,{\rm{purine}} + \alpha {\rm{ - D - pentose - }}1{\rm{ - phosphate}}$$