enzymology Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...

, an uridine phosphorylase () is an

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...

that

catalyzes Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

the

chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...

:uridine + phosphate

\rightleftharpoons

uracil + alpha-D-ribose 1-phosphate Thus, the two substrates of this enzyme are uridine and

phosphate In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid . The phosphate or orthophosphate ion is derived from phospho ...

, whereas its two products are

uracil Uracil () (symbol U or Ura) is one of the four nucleobases in the nucleic acid RNA. The others are adenine (A), cytosine (C), and guanine (G). In RNA, uracil binds to adenine via two hydrogen bonds. In DNA, the uracil nucleobase is replaced by ...

and alpha-D-ribose 1-phosphate. This enzyme belongs to the family of glycosyltransferases, specifically the pentosyltransferases. The systematic name of this enzyme class is uridine:phosphate alpha-D-ribosyltransferase. Other names in common use include pyrimidine phosphorylase, UrdPase, UPH, and UPase. This enzyme participates in

pyrimidine metabolism Pyrimidine biosynthesis occurs both in the body and through organic synthesis. ''De novo'' biosynthesis of pyrimidine ''De Novo'' biosynthesis of a pyrimidine is catalyzed by three gene products CAD, DHODH and UMPS. The first three enzymes of ...

Structural studies

As of late 2007, 27 structures have been solved for this class of enzymes, with PDB accession codes , , , , , , , , , , , , , , , , , , , , , , , , , , and .

References

* * * EC 2.4.2 Enzymes of known structure {{2.4-enzyme-stub