Uridine phosphorylase

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Uridine phosphorylase is an enzyme that plays a crucial role in the metabolism of nucleotides. It is responsible for the breakdown of uridine into uracil and ribose-1-phosphate. This enzyme is found in various organisms, including bacteria, plants, and animals. In humans, uridine phosphorylase is encoded by the UP gene.

Function[edit | edit source]

Uridine phosphorylase is an essential enzyme in the salvage pathway of nucleotide metabolism. It catalyzes the reversible phosphorolysis of uridine, resulting in the release of uracil and ribose-1-phosphate. This reaction allows the recycling of uridine and the generation of ribose-1-phosphate, which can be utilized in the synthesis of nucleotides.

Structure[edit | edit source]

Uridine phosphorylase is a homodimeric enzyme, meaning it consists of two identical subunits. Each subunit contains a catalytic site responsible for the enzymatic activity. The active site of uridine phosphorylase contains a conserved histidine residue that acts as a nucleophile during the phosphorolysis reaction.

Role in Nucleotide Metabolism[edit | edit source]

Uridine phosphorylase is involved in the metabolism of pyrimidine nucleotides. It is responsible for the breakdown of uridine, a pyrimidine nucleoside, into uracil and ribose-1-phosphate. The released uracil can be further metabolized to produce other pyrimidine nucleotides, while ribose-1-phosphate can be utilized in the synthesis of nucleotides or other cellular processes.

Clinical Significance[edit | edit source]

Uridine phosphorylase has been implicated in various diseases and conditions. For example, deficiencies in this enzyme have been associated with hereditary pyrimidine nucleoside phosphorylase (PNP) deficiency, a rare autosomal recessive disorder characterized by immunodeficiency, neurologic abnormalities, and developmental delay. Additionally, uridine phosphorylase has been explored as a potential target for cancer therapy, as its inhibition can lead to the accumulation of toxic nucleoside analogs in cancer cells.

References[edit | edit source]


See Also[edit | edit source]

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Contributors: Prab R. Tumpati, MD