Biochemical Properties
AdK is a monomeric protein (~ 38-40 kDa), which works via an ordered Bi-Bi reaction mechanism. It belongs to the phosphofructokinase B (PfkB) family of sugar kinases. Other members of this family (also known as the RK family) include ribokinase (RK), inosine-guanosine kinase, fructokinase, and 1-phosphofructokinase. The members of the PfkB/RK family are identified by the presence of three conserved sequence motifs. The structures of AdK and several other PfK family of proteins have been determined from a number of organisms (see section below) as well as that for RK protein from E. coli. Despite low sequence similarity between AdK and other PfkB family of proteins, these proteins are quite similar at structural levels. Compounds that are substrates for AdK include the N-nucleosides toyocamycin, tubercidin and 6-methylmecaptopurine riboside; the C-nucleosides formycin A, 9-azadenosine, and a large number of other C- and N-nucleoside analogs. The AdK from mammalian sources, in addition to carrying out ATP-dependent phosphorylation of Ado, also catalyzes an Ado-AMP exchange reaction requiring ADP. This activity is an integral part of AdK and it presumably allows a rapid and precise control of Ado concentration in cells. The enzymatic activity of AdK from different sources show a marked dependence on phosphate (Pi) and/or pentavalent ions and it is a conserved property of the PfkB family of proteins. The conserved NXXE motif, which is a distinctive property of the PfkB family of proteins, is involved in Pi (PVI) dependency.
Read more about this topic: Adenosine Kinase
Famous quotes containing the word properties:
“The reason why men enter into society, is the preservation of their property; and the end why they choose and authorize a legislative, is, that there may be laws made, and rules set, as guards and fences to the properties of all the members of the society: to limit the power, and moderate the dominion, of every part and member of the society.”
—John Locke (1632–1704)