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

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

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

The systematic name of this enzyme class is ATP:d-ribose 5-phosphotransferase. Other names in common use include deoxyribokinase, ribokinase (phosphorylating), and d-ribokinase. This enzyme participates in pentose phosphate pathway.

Ribokinase (RK) belongs to the phosphofructokinase B (PfkB) family of sugar kinases. Other members of this family (also known as the RK family) include adenosine kinase (AK), inosine-guanosine kinase, fructokinase, and 1-phosphofructokinase. 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. 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. 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 (March 1956). (PDF). The Journal of Biological Chemistry. 219 (1): 221–9. doi:. PMID .
  • Ginsburg A (March 1959). (PDF). The Journal of Biological Chemistry. 234 (3): 481–7. doi:. PMID .