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Dihydropyrimidine dehydrogenase (NADP+)

Class of enzymes

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Source updated January 7, 2026

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In enzymology, dihydropyrimidine dehydrogenase (NADP+) (EC 1.3.1.2) is an enzyme that catalyzes the chemical reaction

uracil + NADPH H⁺ H⁺ dihydrouracil + NADP⁺

In the catabolism of uracil, the enzyme converts uracil to dihydrouracil using nicotinamide adenine dinucleotide phosphate (NADPH) as its cofactor. It can also act on thymine to give dihydrothymine.

In humans the enzyme is encoded by the DPYD gene. It is the initial and rate-limiting step in pyrimidine catabolism. It is also involved in the degradation of the chemotherapeutic drugs 5-fluorouracil and tegafur. It participates in beta-alanine metabolism and pantothenate and coa biosynthesis.

01Terminology

The systematic name of this enzyme class is 5,6-dihydrouracil:NADP+ 5-oxidoreductase.
Other names in common use include:

dihydrothymine dehydrogenase
dihydrouracil dehydrogenase (NADP+)
4,5-dihydrothymine: oxidoreductase
DPD
DHPDH
dehydrogenase, dihydrouracil (nicotinamide adenine dinucleotide, phosphate)
DHU dehydrogenase
hydropyrimidine dehydrogenase
dihydropyrimidine dehydrogenase (NADP+)

02Structural studies

As of late 2007, 5 structures have been solved for this class of enzymes, with PDB accession codes PDB: 1GT8, PDB: 1GTE, PDB: 1GTH, PDB: 1H7W, and PDB: 1H7X.

03Function

The protein is a pyrimidine catabolic enzyme and the initial and rate-limiting factor in the pathway of uracil and thymidine catabolism. Genetic deficiency of this enzyme results in an error in pyrimidine metabolism associated with thymine-uraciluria and an increased risk of toxicity in cancer patients receiving 5-fluorouracil chemotherapy.

04Interactive pathway map

Click on genes, proteins and metabolites below to link to respective articles.

Watch videos about Dihydropyrimidine dehydrogenase (NADP+)Explainers and documentaries on YouTube (opens in a new tab)

Sources and credits

This article is adapted from the Wikipedia article “Dihydropyrimidine dehydrogenase (NADP+)”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.

Images, from Wikimedia Commons:

1gte.jpg by Deposition authors: Dobritzsch, D., Ricagno, S., Schneider, G., Schnackerz, K.D., Lindqvist, Y.; visualization author: User:Astrojan, CC BY-SA 4.0

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