Thymidine phosphorylase

In enzymology, a thymidine phosphorylase (EC 2.4.2.4) is an enzyme that catalyzes the chemical reaction

thymidine + phosphate thymine + 2-deoxy-alpha-D-ribose 1-phosphate

Thus, the two substrates of this enzyme are thymidine and phosphate, whereas its two products are thymine and 2-deoxy-alpha-D-ribose 1-phosphate.

Thymidine phosphorylase is involved and used in the diagnosis of mitochondrial neurogastrointestinal encephalomyopathy (MNGIE).

This enzyme belongs to the family of glycosyltransferases, specifically the pentosyltransferases. The systematic name of this enzyme class is thymidine:phosphate deoxy-alpha-D-ribosyltransferase. Other names in common use include pyrimidine phosphorylase, thymidine-orthophosphate deoxyribosyltransferase, animal growth regulators, blood platelet-derived endothelial cell, growth factors, blood platelet-derived endothelial cell growth factor, deoxythymidine phosphorylase, gliostatins, pyrimidine deoxynucleoside phosphorylase, and thymidine:phosphate deoxy-D-ribosyltransferase. This enzyme participates in 3 metabolic pathways: purine metabolism, pyrimidine metabolism, and bladder cancer.

Structural studies

As of late 2007, 6 structures have been solved for this class of enzymes, with PDB accession codes 1AZY, 1OTP, 1TPT, 1UOU, 2J0F, and 2TPT.

References

• FRIEDKIN M, ROBERTS D (1954). "The enzymatic synthesis of nucleosides. I. Thymidine phosphorylase in mammalian tissue". J. Biol. Chem. 207 (1): 245–56. PMID 13152099. 
• Zimmerman M and Seidenberg J (1964). "Deoxyribosyl transfer. I. Thymidine phosphorylase and nucleoside deoxyribosyltransferase in normal and malignant tissues". J. Biol. Chem. 239: 2618–2621. PMID 14235544. 
• Zimmerman M (1964). "Deoxyribosyl transfer. II. Nucleoside:pyrimidine deoxyribosyltransferase activity of three partially purified thymidine phosphorylases". J. Biol. Chem. 239: 2622–2627. PMID 14235545.