Inosine kinase explained

Inosine kinase
Ec Number:	2.7.1.73
Cas Number:	37237-46-0
Go Code:	0008906
Width:	300px

In enzymology, an inosine kinase is an enzyme that catalyzes the chemical reaction

ATP + inosine

\rightleftharpoons ADP + IMP

Thus, the two substrates of this enzyme are ATP and inosine, whereas its two products are ADP and IMP.

Inosine kinase belongs to the phosphofructokinase B (PfkB) family of sugar kinases.^[1] Other members of this family (also known as the Ribokinase family) include ribokinase (RK) adenosine kinase (AK), fructokinase, and 1-phosphofructokinase.^{[2] [3]} The members of the PfkB/RK family are identified by the presence of three conserved sequence motifs.^[4] The structures of several PfK family of proteins have been determined from a number of organisms and the enzymatic activity of this family of this family of protein shows a dependence on the presence of pentavalent ions.^{[5] [4]} Despite low sequence similarity between inosine kinase and other PfkB family of proteins, these proteins are quite similar at structural levels. Other names in common use include inosine-guanosine kinase, and inosine kinase (phosphorylating). This enzyme participates in purine metabolism.

References

• Pierre KJ, LePage GA . 1968 . Formation of inosine-5'-monophosphate by a kinase in cell-free extracts of Ehrlich ascites cells in vitro . Proc. Soc. Exp. Biol. Med. . 127 . 432 - 40 . 5645030 . 2 . 10.3181/00379727-127-32709.

Notes and References

1. Park J, Gupta RS: Adenosine kinase and ribokinase--the RK family of proteins. Cell Mol Life Sci 2008, 65: 2875-2896.
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 Sci 1993, 2: 31-40.
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. Proc Natl Acad Sci U S A 1996, 93: 1232-1237.
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 2002, 41: 4059-4069.
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 1998, 6: 183-193.