PRPP may be synthesized from ribose 5-phosphate by PRPP synthase or, alternately, by the the enzymes phosphopentomutase, ribose 1-phosphokinase (putative), and ribose 1,5-bisphosphokinase [HoveJensen03].
As of May 2003, the identity of the gene (or genes) encoding ribose 1-phosphokinase is not known [HoveJensen03].
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.
The reaction is favored in the direction shown.
HoveJensen03: Hove-Jensen B, Rosenkrantz TJ, Haldimann A, Wanner BL (2003). "Escherichia coli phnN, encoding ribose 1,5-bisphosphokinase activity (phosphoribosyl diphosphate forming): dual role in phosphonate degradation and NAD biosynthesis pathways." J Bacteriol 185(9);2793-801. PMID: 12700258
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