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[Biochemistry](https://durgical.com/en/biochemistry/) · Molecule

# PRPP (phosphoribosyl pyrophosphate)

PRPP is activated ribose: the starting point for making and recycling every nucleotide.

Updated 2026-11-01

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## Key facts

- It is made from ribose-5-phosphate and ATP by PRPP synthetase.
- It is used by de novo purine synthesis (committed step), pyrimidine synthesis (UMP synthase), base salvage (HGPRT, APRT) and NAD⁺ synthesis.
- Its concentration controls purine synthesis: more PRPP, more amidotransferase activity.
- It rises in HGPRT deficiency and in PRPP synthetase superactivity: both cause hyperuricaemia.

**Also called**
5-Phosphoribosyl-1-pyrophosphate

**Formula**
C₅H₁₃O₁₄P₃

**PubChem**
[CID 7339](https://pubchem.ncbi.nlm.nih.gov/compound/7339)

## Structure

- A ribofuranose ring with a phosphate on C5 and an α-pyrophosphate on C1.
- When a base attaches, the pyrophosphate leaves and the bond ends up β, as in nucleotides.

## Clinical notes

- In Lesch-Nyhan syndrome PRPP unused by HGPRT accumulates in red cells and speeds purine synthesis.
- Hydrolysis of the released pyrophosphate makes PRPP-using reactions irreversible.

## Pathways

- [De novo purine synthesis](https://durgical.com/en/biochemistry/pathways/de-novo-purine-synthesis/)
- [Pyrimidine synthesis](https://durgical.com/en/biochemistry/pathways/pyrimidine-synthesis/)
- [Purine degradation and salvage](https://durgical.com/en/biochemistry/pathways/purine-degradation-and-salvage/)

## Related conditions

- [Gout](https://durgical.com/en/conditions/gout/)
- [Lesch-Nyhan syndrome](https://durgical.com/en/conditions/lesch-nyhan-syndrome/)

## Related

- [PRPP synthetase](https://durgical.com/en/biochemistry/enzymes/prpp-synthetase/)
- [Glutamine-PRPP amidotransferase](https://durgical.com/en/biochemistry/enzymes/glutamine-prpp-amidotransferase/)
- [Hypoxanthine-guanine phosphoribosyltransferase (HGPRT)](https://durgical.com/en/biochemistry/enzymes/hypoxanthine-guanine-phosphoribosyltransferase/)
- [Adenine phosphoribosyltransferase (APRT)](https://durgical.com/en/biochemistry/enzymes/adenine-phosphoribosyltransferase/)
- [UMP synthase](https://durgical.com/en/biochemistry/enzymes/ump-synthase/)
- [NAD⁺ (nicotinamide adenine dinucleotide)](https://durgical.com/en/biochemistry/molecules/nad/)

## Test yourself

Think of the answer, then tap the question to see it.

## Which enzyme makes PRPP, and from what?

PRPP synthetase, from ribose-5-phosphate and ATP (which is left as AMP).

## Why does PRPP rise in HGPRT deficiency?

HGPRT is a major PRPP consumer; without it PRPP is left over and stimulates de novo purine synthesis.

## How does PRPP use differ between purines and pyrimidines?

In purines the ring is built on PRPP; in pyrimidines the finished ring (orotate) is attached to PRPP.

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Molecules are shown in their neutral form, as the databases deposit them; in the cell the acids and phosphates are ionised.

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Phosphoribosyl Pyrophosphate (CID 7339)](https://pubchem.ncbi.nlm.nih.gov/compound/7339) (PubChem, NCBI, 2026) · Public domain; [Purine ribonucleoside monophosphate biosynthesis](https://reactome.org/PathwayBrowser/#/R-HSA-73817) (Reactome, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/biochemistry/molecules/prpp/
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