Ribokinase

{{infobox enzyme | Name = ribokinase | EC_number = 2.7.1.15 | CAS_number = 9026-84-0 | GO_code = 0004747 | image = 5byf.jpg | width = 270 | caption = Ribokinase dimer, Human }} In enzymology, a '''ribokinase''' ({{EC number|2.7.1.15}}) is an enzyme that catalyzes the chemical reaction

:ATP + {{sm|d}}-ribose ⇌ ADP + {{sm|d}}-ribose 5-phosphate

Thus, the two substrates of this enzyme are ATP and {{sm|d}}-ribose, whereas its two products are ADP and {{sm|d}}-ribose 5-phosphate.

The systematic name of this enzyme class is '''ATP:{{sm|d}}-ribose 5-phosphotransferase'''. Other names in common use include '''deoxyribokinase''', '''ribokinase (phosphorylating)''', and '''{{sm|d}}-ribokinase'''. This enzyme participates in pentose phosphate pathway. Ribokinase (RK) belongs to the phosphofructokinase B (PfkB) family of sugar kinases.<ref name=Park>{{cite journal | vauthors = Park J, Gupta RS | title = Adenosine kinase and ribokinase--the RK family of proteins | journal = Cellular and Molecular Life Sciences | volume = 65 | issue = 18 | pages = 2875–96 | date = September 2008 | pmid = 18560757 | doi = 10.1007/s00018-008-8123-1 | s2cid = 11439854 | pmc = 11131688 }}</ref> Other members of this family (also known as the RK family) include adenosine kinase (AK), inosine-guanosine kinase, fructokinase, and 1-phosphofructokinase.<ref name=Park /><ref name=Bork>{{cite journal | vauthors = Bork P, Sander C, Valencia A | title = Convergent evolution of similar enzymatic function on different protein folds: the hexokinase, ribokinase, and galactokinase families of sugar kinases | journal = Protein Science | volume = 2 | issue = 1 | pages = 31–40 | date = January 1993 | pmid = 8382990 | pmc = 2142297 | doi = 10.1002/pro.5560020104 | doi-access = free | authorlink1 = Peer Bork | authorlink2 = Chris Sander (scientist) | authorlink3 = Alfonso Valencia }}</ref><ref name=Spychala>{{cite journal | vauthors = Spychala J, Datta NS, Takabayashi K, Datta M, Fox IH, Gribbin T, Mitchell BS | title = Cloning of human adenosine kinase cDNA: sequence similarity to microbial ribokinases and fructokinases | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 93 | issue = 3 | pages = 1232–7 | date = February 1996 | pmid = 8577746 | pmc = 40062 | doi = 10.1073/pnas.93.3.1232 | bibcode = 1996PNAS...93.1232S | doi-access = free }}</ref> The members of the PfkB/RK family are identified by the presence of three conserved sequence motifs and the enzymatic activity of this family of protein generally shows a dependence on the presence of pentavalent ions.<ref name=Park /><ref name=Bork /><ref>{{cite journal | vauthors = Maj MC, Singh B, Gupta RS | title = Pentavalent ions dependency is a conserved property of adenosine kinase from diverse sources: identification of a novel motif implicated in phosphate and magnesium ion binding and substrate inhibition | journal = Biochemistry | volume = 41 | issue = 12 | pages = 4059–69 | date = March 2002 | pmid = 11900549 | doi = 10.1021/bi0119161 }}</ref> The conserved NXXE motif, which is a distinctive property of the PfkB family of proteins, is involved in pentavalent ion dependency. The structures of RK and several other PfK family of proteins have been determined from a number of organisms.<ref>{{cite journal | vauthors = Sigrell JA, Cameron AD, Jones TA, Mowbray SL | title = Structure of Escherichia coli ribokinase in complex with ribose and dinucleotide determined to 1.8 A resolution: insights into a new family of kinase structures | journal = Structure | volume = 6 | issue = 2 | pages = 183–93 | date = February 1998 | pmid = 9519409 | doi = 10.1016/s0969-2126(98)00020-3 | doi-access = free | authorlink3 = Alwyn Jones (biophysicist) }}</ref> Despite low sequence similarity between AdK and other PfkB family of proteins, these proteins are quite similar at structural levels.<ref name=Park />

==Structural studies==

As of late 2007, 7 structures have been solved for this class of enzymes, with PDB accession codes {{PDB2|1GQT}}, {{PDB2|1RK2}}, {{PDB2|1RKA}}, {{PDB2|1RKD}}, {{PDB2|1RKS}}, {{PDB2|1VM7}}, and {{PDB2|2FV7}}.

== References == {{reflist}}

== Further reading == {{refbegin}} * {{cite journal | vauthors = Agranoff BW, Brady RO | title = Purification and properties of calf liver ribokinase | journal = The Journal of Biological Chemistry | volume = 219 | issue = 1 | pages = 221–9 | date = March 1956 | doi = 10.1016/S0021-9258(18)65786-2 | pmid = 13295274 | url = http://www.jbc.org/content/219/1/221.full.pdf | authorlink2 = Roscoe Brady | doi-access = free }} * {{cite journal | vauthors = Ginsburg A | title = A deoxyribokinase from Lactobacillus plantarum | journal = The Journal of Biological Chemistry | volume = 234 | issue = 3 | pages = 481–7 | date = March 1959 | doi = 10.1016/S0021-9258(18)70230-5 | pmid = 13641245 | url = http://www.jbc.org/content/234/3/481.full.pdf | doi-access = free }} {{refend}}

Category:EC 2.7.1 Category:Enzymes of known structure