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{{enzyme
| Name = purine nucleosidase
| EC_number = 3.2.2.1
| CAS_number = 9025-44-9
| IUBMB_EC_number = 3/2/2/1
| GO_code = 0008477
| image = 
| width = 
| caption = 
}}
In [[enzymology]], a '''purine nucleosidase''' ({{EC number|3.2.2.1}}) is an [[enzyme]] that [[catalysis|catalyzes]] the [[chemical reaction]]

:a purine nucleoside + H<sub>2</sub>O <math>\rightleftharpoons</math> D-ribose + a purine base

Thus, the two [[substrate (biochemistry)|substrates]] of this enzyme are [[purine nucleoside]] and [[water|H<sub>2</sub>O]], whereas its two [[product (chemistry)|products]] are [[D-ribose]] and [[purine base]].

This enzyme belongs to the family of [[hydrolase]]s, specifically those glycosylases that hydrolyse N-glycosyl compounds.  The systematic name of this enzyme class is '''purine-nucleoside ribohydrolase'''. Other names in common use include '''nucleosidase''', '''purine beta-ribosidase''', '''purine nucleoside hydrolase''', '''purine ribonucleosidase''', '''ribonucleoside hydrolase''', '''nucleoside hydrolase''', '''N-ribosyl purine ribohydrolase''', '''nucleosidase g''', '''N-D-ribosylpurine ribohydrolase''', '''inosine-adenosine-guanosine preferring nucleoside hydrolase''', '''purine-specific nucleoside N-ribohydrolase''', '''IAG-nucleoside hydrolase''', and '''IAG-NH'''.  This enzyme participates in [[purine metabolism]] and [[nicotinate and nicotinamide metabolism]].

==Structural studies==

As of late 2007, 11 [[tertiary structure|structures]] have been solved for this class of enzymes, with [[Protein Data Bank|PDB]] accession codes {{PDB link|1EZR}}, {{PDB link|1HOZ}}, {{PDB link|1HP0}}, {{PDB link|1KIC}}, {{PDB link|1KIE}}, {{PDB link|1MAS}}, {{PDB link|1R4F}}, {{PDB link|2C40}}, {{PDB link|2FF1}}, {{PDB link|2FF2}}, and {{PDB link|2MAS}}.

==References==
{{reflist|1}}
* {{cite journal | author = HEPPEL LA, HILMOE RJ | year = 1952 | title = [Phosphorolysis and hydrolysis of purine ribosides by enzymes from yeast.] | journal = J. Biol. Chem.  | volume = 198 | pages = 683&ndash;94  | pmid = 12999785 | issue = 2 }}
* {{cite journal | author = Kalckar HM | date = Napoli | title = Biosynthetic aspects of nucleosides and nucleic acids | journal = Pubbl. Staz.  | volume = Zool. | pages = 87&ndash;103 }}
* {{cite journal | author = Takagi Y and Horecker BL | year = 1956 | title = Purification and properties of a bacterial riboside hydrolyase | journal = J. Biol. Chem.  | volume = 225 | pages = 77&ndash;86 | pmid=13416219 | issue = 1}}
* {{cite journal | author = Tarr HLA | year = 1955 | title = Fish muscle riboside hydrolases | journal = Biochem. J.  | volume = 59 | pages = 386&ndash;391 }}
* {{cite journal | author = Parkin DW | year = 1996 | title = Purine-specific nucleoside N-ribohydrolase from Trypanosoma brucei brucei. Purification, specificity, and kinetic mechanism | journal = J. Biol. Chem.  | volume = 271 | pages = 21713&ndash;9  | pmid = 8702965 | issue = 36 | doi = 10.1074/jbc.271.36.21713}}
* {{cite journal | author = S | year = 2001 | title = Purification, characterization, and gene cloning of purine nucleosidase from Ochrobactrum anthropi | journal = Appl. Environ. Microbiol.  | volume = 67 | pages = 1783&ndash;7  | pmid = 11282633 | doi = 10.1128/AEM.67.4.1783-1787.2001 | last2 = Takeda | first2 = S | last3 = Xie | first3 = SX | last4 = Hatanaka | first4 = H | last5 = Ashikari | first5 = T | last6 = Amachi | first6 = T | last7 = Shimizu | first7 = S | issue = 4 | pmc = 92797 }}
* {{cite journal | author = Versees W, Decanniere K, Van Holsbeke E, Devroede N, Steyaert J | year = 2002 | title = Enzyme-substrate interactions in the purine-specific nucleoside hydrolase from Trypanosoma vivax | journal = J. Biol. Chem.  | volume = 277 | pages = 15938&ndash;46  | pmid = 11854281 | doi = 10.1074/jbc.M111735200 | issue = 18 }}
* {{cite journal | author = Mazumder-Shivakumar D, Bruice TC | year = 2005 | title = Computational study of IAG-nucleoside hydrolase: determination of the preferred ground state conformation and the role of active site residues | journal = Biochemistry.  | volume = 44 | pages = 7805&ndash;17  | pmid = 15909995 | doi = 10.1021/bi047394h | issue = 21 }}

[[Category:EC 3.2.2]]
[[Category:Enzymes of known structure]]


{{hydrolase-stub}}