Editing Dehydrogenase (section)

=== Identifying a dehydrogenase reaction ===
The distinction between the subclasses of oxidoreductases that catalyze oxidation reactions lies in their electron acceptors.<ref name=":1">{{Cite book
|title = Fundamentals of Biochemistry: Life at the Molecular Level
|last1 = Voet |first1 = Donald
|last2 = Voet |first2 = Judith G.
|last3 = Pratt |first3 = Charlotte W.
|edition = 5th
|publisher = Wiley
|date = 2016
|location = New York
|isbn =  9781118918401
}}</ref>
[[File:Vanillyl-alcohol oxidase reaction.PNG|thumb|Reaction catalyzed by an oxidase, note the reduction of oxygen as the electron acceptor]]
Dehydrogenase and [[oxidase]] are easily distinguishable if one considers the electron acceptor.  An oxidase will remove electrons from a substrate as well, but only uses oxygen as its electron acceptor. One such reaction is: AH<sub>2</sub> + O<sub>2</sub> ↔ A + H<sub>2</sub>O<sub>2</sub>.

Sometimes an oxidase reaction will look like this: 4A + 4H<sup>+</sup> + O<sub>2</sub> ↔ 4A<sup>+</sup> + 2H<sub>2</sub>O. In this case, the enzyme is taking electrons from the substrate, and using free protons to reduce the oxygen, leaving the substrate with a positive charge. The product is water, instead of hydrogen peroxide as seen above. An example of an oxidase that functions like this is complex IV in the Electron Transport Chain ([[Electron transport chain|ETC]]).<ref>{{Cite journal|last1=Yoshikawa|first1=Shinya|last2=Shimada|first2=Atsuhiro|date=2015-01-20|title=Reaction Mechanism of Cytochrome c Oxidase|journal=Chemical Reviews|language=EN|volume=115|issue=4|pages=1936–1989|doi=10.1021/cr500266a|pmid=25603498}}</ref>

Note that oxidases typically transfer the equivalent of dihydrogen (H<sub>2</sub>), and the acceptor is a dioxygen. Similarly, a [[peroxidase]] (another subclass of oxidoreductases) will use a peroxide (H<sub>2</sub>O<sub>2</sub>) as the electron acceptor, rather than an oxygen.<ref name=":4" />