In enzymology, a ribokinase () is an enzyme that catalyzes the chemical reaction
The enzyme originally characterised from calf liver and Lactobacillus plantarum converts the pentose sugar, D-ribose (shown in its open-chain aldehydo form), to ribose 5-phosphate by transferring a phosphate group from the cofactor, adenosine triphosphate (ATP), which is converted to adenosine diphosphate (ADP).
The systematic name of this enzyme class is ATP:-ribose 5-phosphotransferase. Other names in common use include deoxyribokinase, ribokinase (phosphorylating), and -ribokinase.
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 .
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