In enzymology, a ribokinase (EC 184.108.40.206) 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.
As of late 2007, 7 structures have been solved for this class of enzymes, with PDB accession codes 1GQT, 1RK2, 1RKA, 1RKD, 1RKS, 1VM7, and 2FV7.
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