Editing Kinase (section)

==Carbohydrate kinases==
[[File:Glycolysis including irreversible steps.png|frameless|Glycolysis includes four phosphorylations, two that create ATP from ADP and two that use ATP and converting it into ADP. Glycolysis is the first step of metabolism and includes ten reaction ultimately resulting in one glucose molecule producing two pyruvate molecules]]

For many mammals, carbohydrates provide a large portion of the daily [[calorie|caloric]] requirement. To harvest energy from [[oligosaccharide]]s, they must first be broken down into [[monosaccharide]]s so they can enter [[cellular metabolism|metabolism]]. Kinases play an important role in almost all metabolic pathways. The figure on the left shows the second phase of [[glycolysis]], which contains two important reactions catalyzed by kinases. The [[anhydride]] linkage in 1,3 bisphosphoglycerate is unstable and has a high energy. 1,3-bisphosphogylcerate kinase requires ADP to carry out its reaction yielding 3-phosphoglycerate and ATP. In the final step of glycolysis, pyruvate kinase transfers a phosphoryl group from [[phosphoenolpyruvate]] to ADP, generating ATP and pyruvate.

'''[[Hexokinase]]''' is the most common enzyme that makes use of glucose when it first enters the cell. It converts D-glucose to glucose-6-phosphate by transferring the gamma phosphate of an ATP to the C6 position. This is an important step in glycolysis because it traps glucose inside the cell due to the negative charge. In its dephosphorylated form, glucose can move back and forth across the membrane very easily.<ref name=Carb>{{cite journal | vauthors = Holzer H, Duntze W | title = Metabolic regulation by chemical modification of enzymes | journal = Annual Review of Biochemistry | volume = 40 | pages = 345–374 | year = 1971 | pmid = 4399446 | doi = 10.1146/annurev.bi.40.070171.002021 }}</ref> Mutations in the hexokinase gene can lead to a [[hexokinase deficiency]] which can cause nonspherocytic hemolytic [[anemia]].<ref>{{cite web|title=Nonspherocytic hemolytic anemia due to hexokinase deficiency|url=http://rarediseases.info.nih.gov/gard/3672/nonspherocytic-hemolytic-anemia-due-to-hexokinase-deficiency/resources/1|access-date=2014-02-24|archive-date=2015-09-05|archive-url=https://web.archive.org/web/20150905121422/https://rarediseases.info.nih.gov/gard/3672/nonspherocytic-hemolytic-anemia-due-to-hexokinase-deficiency/resources/1|url-status=dead}}</ref>

'''[[Phosphofructokinase]]''', or PFK, catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate and is an important point in the regulation of glycolysis. High levels of ATP, H<sup>+</sup>, and [[citrate]] inhibit PFK. If citrate levels are high, it means that glycolysis is functioning at an optimal rate. High levels of [[adenosine monophosphate|AMP]] stimulate PFK. [[Tarui's disease]], a glycogen storage disease that leads to exercise intolerance, is due to a mutation in the PFK gene that reduces its activity.<ref>{{cite web|title=Phosphofructokinase Deficiency Glycogen Storage Disease|url=http://www.patient.co.uk/doctor/phosphofructokinase-deficiency-glycogen-storage-disease}}</ref>