Thymidine phosphorylase | |||||||||
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Thymidine phosphorylase protein structure
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Identifiers | |||||||||
EC number | 2.4.2.4 | ||||||||
CAS number | 9030-23-3 | ||||||||
Databases | |||||||||
IntEnz | IntEnz view | ||||||||
BRENDA | BRENDA entry | ||||||||
ExPASy | NiceZyme view | ||||||||
KEGG | KEGG entry | ||||||||
MetaCyc | metabolic pathway | ||||||||
PRIAM | profile | ||||||||
PDB structures | RCSB PDB PDBe PDBsum | ||||||||
Gene Ontology | AmiGO / EGO | ||||||||
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Search | |
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PMC | articles |
PubMed | articles |
NCBI | proteins |
In enzymology, a thymidine phosphorylase (EC 2.4.2.4) is an enzyme that catalyzes the chemical reaction
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.
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 is involved in metabolic pathways: purine metabolism/pyrimidine metabolism, bladder cancer, and in the diagnosis of mitochondrial neurogastrointestinal encephalomyopathy (MNGIE).
Thymidine phosphorylase catalyzes the reversible phosphorylation of thymidine, deoxyuridine, and their analogs (except deoxycytidine) to their respective bases (thymine/uracil) and 2-deoxyribose 1-phosphate. The enzyme follows a sequential mechanism, where phosphate binds before thymidine (or deoxyuridine, etc.) and 2-deoxyribose 1-phosphate leaves after the nitrogenous base. The thymidine is bound in a high-energy conformation, in which the glycosidic bond weakens as the phosphate attacks the C1 position of the ribose ring, as shown below. The enzyme can then transfer deoxyribose 1-phosphate to other nitrogenous bases.