Editing Kinase (section)

==Other kinases==
[[File:Riboflavin kinase.png|thumb|The active site of riboflavin kinase bound to its products--FMN (on left) and ADP (on right). Coordinates from PDB ID: 1N07.<ref>{{cite journal | vauthors = Bauer S, Kemter K, Bacher A, Huber R, Fischer M, Steinbacher S | title = Crystal structure of Schizosaccharomyces pombe riboflavin kinase reveals a novel ATP and riboflavin-binding fold | journal = Journal of Molecular Biology | volume = 326 | issue = 5 | pages = 1463–1473 | date = March 2003 | pmid = 12595258 | doi = 10.1016/s0022-2836(03)00059-7 }}</ref>]]
Kinases act upon many other molecules besides proteins, lipids, and carbohydrates. There are many that act on nucleotides (DNA and RNA) including those involved in nucleotide interconverstion, such as [[nucleoside-phosphate kinase]]s and [[nucleoside-diphosphate kinase]]s.<ref>{{cite book | vauthors = Voet D, Voet JC, Pratt CW |title=Fundamentals of biochemistry : life at the molecular level|year=2008|publisher=Wiley|location=Hoboken, NJ|isbn=9780470129302|edition=3rd}}</ref> Other small molecules that are substrates of kinases include [[creatine]], [[phosphoglycerate]], [[riboflavin]], [[dihydroxyacetone]], [[shikimate]], and many others.

===Riboflavin kinase===
{{main|Riboflavin kinase}}Riboflavin kinase catalyzes the phosphorylation of [[riboflavin]] to create [[flavin mononucleotide]](FMN). It has an ordered binding mechanism where riboflavin must bind to the kinase before it binds to the ATP molecule.<ref name="sdf">{{cite journal | vauthors = Karthikeyan S, Zhou Q, Osterman AL, Zhang H | title = Ligand binding-induced conformational changes in riboflavin kinase: structural basis for the ordered mechanism | journal = Biochemistry | volume = 42 | issue = 43 | pages = 12532–12538 | date = November 2003 | pmid = 14580199 | doi = 10.1021/bi035450t }}</ref> [[Divalent]] [[cation]]s help coordinate the [[nucleotide]].<ref name="sdf" /> The general mechanism is shown in the figure below.[[File:Riboflavin mechanism.png|thumb|upright=2.5|center|Mechanism of riboflavin kinase.]]
Riboflavin kinase plays an important role in cells, as [[flavin mononucleotide|FMN]] is an important [[cofactor (biochemistry)|cofactor]]. [[flavin mononucleotide|FMN]] also is a precursor to [[flavin adenine dinucleotide]](FAD), a [[redox cofactor]] used by many enzymes, including many in [[metabolism]]. In fact, there are some enzymes that are capable of carrying out both the phosphorylation of riboflavin to [[flavin mononucleotide|FMN]], as well as the [[flavin mononucleotide|FMN]] to [[flavin adenine dinucleotide|FAD]] reaction.<ref>{{cite journal | vauthors = Galluccio M, Brizio C, Torchetti EM, Ferranti P, Gianazza E, Indiveri C, Barile M | title = Over-expression in Escherichia coli, purification and characterization of isoform 2 of human FAD synthetase | journal = Protein Expression and Purification | volume = 52 | issue = 1 | pages = 175–181 | date = March 2007 | pmid = 17049878 | doi = 10.1016/j.pep.2006.09.002 }}</ref> Riboflavin kinase may help prevent stroke, and could possibly be used as a treatment in the future.<ref>{{cite journal | vauthors = Zou YX, Zhang XH, Su FY, Liu X | title = Importance of riboflavin kinase in the pathogenesis of stroke | journal = CNS Neuroscience & Therapeutics | volume = 18 | issue = 10 | pages = 834–840 | date = October 2012 | pmid = 22925047 | pmc = 6493343 | doi = 10.1111/j.1755-5949.2012.00379.x }}</ref> It is also implicated in infection, when studied in mice.<ref>{{cite journal | vauthors = Brijlal S, Lakshmi AV, Bamji MS, Suresh P | title = Flavin metabolism during respiratory infection in mice | journal = The British Journal of Nutrition | volume = 76 | issue = 3 | pages = 453–462 | date = September 1996 | pmid = 8881717 | doi = 10.1079/BJN19960050 | doi-access = free }}</ref>

===Thymidine kinase===
{{main|Thymidine kinase}}
[[Thymidine kinase]] is one of the many nucleoside kinases that are responsible for nucleoside phosphorylation. It phosphorylates [[thymidine]] to create [[thymidine monophosphate]] (dTMP). This kinase uses an ATP molecule to supply the [[phosphate]] to thymidine, as shown below. This transfer of a phosphate from one nucleotide to another by thymidine kinase, as well as other nucleoside and nucleotide kinases, functions to help control the level of each of the different nucleotides.

[[File:Thymidine kinase.png|thumb|center|upright=2.5|Overall reaction catalysed by thymidine kinase.]]

After creation of the dTMP molecule, another kinase, [[thymidylate kinase]], can act upon dTMP to create the [[thymidine diphosphate|diphosphate]] form, dTDP. [[Nucleoside-diphosphate kinase|Nucleoside diphosphate kinase]] catalyzes production of [[thymidine triphosphate]], dTTP, which is used in [[DNA synthesis]]. Because of this, thymidine kinase activity is closely correlated with the [[cell cycle]] and used as a [[tumor marker]] in [[Thymidine kinase in clinical chemistry|clinical chemistry]].<ref>{{cite journal | vauthors = Aufderklamm S, Todenhöfer T, Gakis G, Kruck S, Hennenlotter J, Stenzl A, Schwentner C | title = Thymidine kinase and cancer monitoring | journal = Cancer Letters | volume = 316 | issue = 1 | pages = 6–10 | date = March 2012 | pmid = 22068047 | doi = 10.1016/j.canlet.2011.10.025 }}</ref> Therefore, it can sometime be used to predict patient prognosis.<ref>{{cite journal | vauthors = Topolcan O, Holubec L | title = The role of thymidine kinase in cancer diseases | journal = Expert Opinion on Medical Diagnostics | volume = 2 | issue = 2 | pages = 129–141 | date = February 2008 | pmid = 23485133 | doi = 10.1517/17530059.2.2.129 }}</ref> Patients with mutations in the thymidine kinase [[gene]] may have a certain type of [[mitochondrial DNA]] depletion [[syndrome]], a disease that leads to death in early childhood.<ref>{{cite journal | vauthors = Götz A, Isohanni P, Pihko H, Paetau A, Herva R, Saarenpää-Heikkilä O, Valanne L, Marjavaara S, Suomalainen A | display-authors = 6 | title = Thymidine kinase 2 defects can cause multi-tissue mtDNA depletion syndrome | journal = Brain | volume = 131 | issue = Pt 11 | pages = 2841–2850 | date = November 2008 | pmid = 18819985 | doi = 10.1093/brain/awn236 | doi-access = free }}</ref>