Phosphoribosyl pyrophosphate (PRPP) is a pentosephosphate.It is formed from ribose 5-phosphate by the enzyme ribose-phosphate diphosphokinase.In de novo generation of purines, the enzyme amidophosphoribosyltransferase acts upon PRPP to create phosphoribosylamine. Phosphoribosyl pyrophosphate (PRPP) is a central compound for cellular metabolism and may be considered as a link between carbon and nitrogen metabolism. PRPP is directly involved in the de novo and salvage biosynthesis of GTP, which is the immediate precursor of riboflavin. PRPP is a biosynthetic precursor of histidine and tryptophan, and it is also required for the de novo and salvage pathways of purine, pyrimidine and pyridine (NAD⁺, NADP⁺) nucleotides. It has been calculated that approximately 80% of the metabolic flux through PRPP is directed to purine and pyrimidine synthesis