Ribokinase Explained

ribokinase
Ec Number:	2.7.1.15
Cas Number:	9026-84-0
Go Code:	0004747
Width:	270

In enzymology, a ribokinase is an enzyme that catalyzes the chemical reaction

ATP + -ribose ⇌ ADP + -ribose 5-phosphate

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

The systematic name of this enzyme class is ATP:-ribose 5-phosphotransferase. Other names in common use include deoxyribokinase, ribokinase (phosphorylating), and -ribokinase. This enzyme participates in pentose phosphate pathway. Ribokinase (RK) belongs to the phosphofructokinase B (PfkB) family of sugar kinases.^[1] Other members of this family (also known as the RK family) include adenosine kinase (AK), inosine-guanosine kinase, fructokinase, and 1-phosphofructokinase.^{[2] [3]} 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.^[4] 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.^[5] Despite low sequence similarity between AdK and other PfkB family of proteins, these proteins are quite similar at structural levels.

Structural studies

As of late 2007, 7 structures have been solved for this class of enzymes, with PDB accession codes,,,,,, and .

Further reading

• Agranoff BW, Brady RO . Purification and properties of calf liver ribokinase . The Journal of Biological Chemistry . 219 . 1 . 221–9 . March 1956 . 10.1016/S0021-9258(18)65786-2 . 13295274 . Roscoe Brady . free .
• Ginsburg A . A deoxyribokinase from Lactobacillus plantarum . The Journal of Biological Chemistry . 234 . 3 . 481–7 . March 1959 . 10.1016/S0021-9258(18)70230-5 . 13641245 . free .

Notes and References

1. Park J, Gupta RS . Adenosine kinase and ribokinase--the RK family of proteins . Cellular and Molecular Life Sciences . 65 . 18 . 2875–96 . September 2008 . 18560757 . 10.1007/s00018-008-8123-1 . 11439854 . 11131688 .
2. Bork P, Sander C, Valencia A . Convergent evolution of similar enzymatic function on different protein folds: the hexokinase, ribokinase, and galactokinase families of sugar kinases . Protein Science . 2 . 1 . 31–40 . January 1993 . 8382990 . 2142297 . 10.1002/pro.5560020104 . free . Peer Bork . Chris Sander (scientist) . Alfonso Valencia .
3. Spychala J, Datta NS, Takabayashi K, Datta M, Fox IH, Gribbin T, Mitchell BS . Cloning of human adenosine kinase cDNA: sequence similarity to microbial ribokinases and fructokinases . Proceedings of the National Academy of Sciences of the United States of America . 93 . 3 . 1232–7 . February 1996 . 8577746 . 40062 . 10.1073/pnas.93.3.1232 . 1996PNAS...93.1232S . free .
4. Maj MC, Singh B, Gupta RS . 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 . Biochemistry . 41 . 12 . 4059–69 . March 2002 . 11900549 . 10.1021/bi0119161 .
5. Sigrell JA, Cameron AD, Jones TA, Mowbray SL . 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 . Structure . 6 . 2 . 183–93 . February 1998 . 9519409 . 10.1016/s0969-2126(98)00020-3 . free . Alwyn Jones (biophysicist) .