View source for Dikinase

'''Dikinases'''  are a category of enzymes that [[catalysis|catalyze]] the [[chemical reaction]]

:ATP + X + Y <math>\rightleftharpoons</math> AMP + X-''P'' + Y-''P''.

Dikinases are all [[phosphotransferase]]s. Their designated [[Enzyme Commission number|EC number]] is [[List_of_EC_numbers_(EC_2)#EC_2.7.9:_Phosphotransferases with paired acceptors (dikinases)|2.7.9]]. It is one of the smallest groups of phosphotransferases.

==Function==
Dikinases take two [[phosphate]] groups from [[Adenosine triphosphate|ATP]] and [[transferase|transfer]] each one to a different acceptor. This results in [[Adenosine monophosphate|AMP]] and two different [[phosphorylation|phosphorylated]] compounds. In most dikinases, one of the acceptors is [[water]]. In at least one dikinase ([[pyruvate, phosphate dikinase]]), one of the acceptors is inorganic phosphate, resulting in diphosphate. 

For the dikinases that use water as acceptor, it has been shown that the ''γ''-phosphate of ATP (the third, most distant phosphate) is transferred to water, whereas the ''β''-phosphate (the middle phosphate) is transferred to the other acceptor. It has also been shown that the enzyme first phosphorylates itself ([[autophosphorylation]]). After transfer of the ''γ''-phosphate to water, the ''β''-phosphate is first transferred to a [[histidine]] [[residue (chemistry)|residue]] on the enzyme, and later to the final acceptor.

Dikinases are commonly named as follows: '''first acceptor, second acceptor kinase'''. Examples:
* [[Phosphoglucan, water dikinase]],
* [[Selenide, water dikinase]].

Dikinases should not be confused with [[diphosphotransferase]]s (EC 2.7.6), which are phosphotransferases which act upon [[pyrophosphate]] groups.

[[Category:EC 2.7.9|*]]
[[Category:Enzymes]]


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