View source for Polygalacturonate 4-alpha-galacturonosyltransferase

{{enzyme
| Name = pyrimidine-nucleoside phosphorylase
| EC_number = 2.4.2.2
| CAS_number = 9055-35-0
| IUBMB_EC_number = 2/4/2/2
| GO_code = 0016154
| image = 
| width = 
| caption = 
}}
In [[enzymology]], a '''pyrimidine-nucleoside phosphorylase''' ({{EC number|2.4.2.2}}) is an [[enzyme]] that [[catalysis|catalyzes]] the [[chemical reaction]]

:a pyrimidine nucleoside + phosphate <math>\rightleftharpoons</math> a pyrimidine base + alpha-D-ribose 1-phosphate

Thus, the two [[substrate (biochemistry)|substrates]] of this enzyme are [[pyrimidine nucleoside]] and [[phosphate]], whereas its two [[product (chemistry)|products]] are [[pyrimidine base]] and [[alpha-D-ribose 1-phosphate]].

This enzyme belongs to the family of [[glycosyltransferase]]s, specifically the pentosyltransferases.  The systematic name of this enzyme class is '''pyrimidine-nucleoside:phosphate alpha-D-ribosyltransferase'''. This enzyme is also called '''Py-NPase'''.  This enzyme participates in [[pyrimidine metabolism]].  

==Structural studies==

As of late 2007, two [[tertiary structure|structures]] have been solved for this class of enzymes, with [[Protein Data Bank|PDB]] accession codes {{PDB link|1BRW}} and {{PDB link|2DSJ}}.

==References==
{{reflist|1}}
* Boyer, P.D., Lardy, H. and Myrback, K. (Eds.), The Enzymes, 2nd ed., vol. 5, Academic Press, New York, 1961, p. 237-255.
* {{cite journal | author = Saunders PP, Wilson BA, Saunders GF | date = 1969 | title = Purification and comparative properties of a pyrimidine nucleoside phosphorylase from Bacillus stearothermophilus | journal = J. Biol. Chem.  | volume = 244 | pages = 3691&ndash;7  | pmid = 4978445 | issue = 13 }}
* {{cite journal | doi = 10.1271/bbb.60.1179 | author = Hamamoto T, Noguchi T, Midorikawa Y | date = 1996 | title = Purification and characterization of purine nucleoside phosphorylase and pyrimidine nucleoside phosphorylase from Bacillus stearothermophilus TH 6-2 | journal = Biosci. Biotechnol. Biochem.  | volume = 60 | pages = 1179&ndash;80  | pmid = 8782414 | issue = 7 }}

{{enzyme-stub}}

[[Category:EC 2.4.2]]
[[Category:Enzymes of known structure]]