View source for Hydrogen peroxide

{{Technical service}}
{{MitoPedia
|abbr=H<sub>2</sub>O<sub>2</sub>
|description=[[File:H2O2.jpg|left|60px|Hydrogen peroxide]]
'''Hydrogen peroxide''', H<sub>2</sub>O<sub>2</sub> or dihydrogen dioxide, is one of several reactive oxygen intermediates generally referred to as [[reactive oxygen species]] (ROS). It is formed in various enzyme-catalyzed reactions (e.g. [[superoxide dismutase]]) with the potential to damage cellular molecules and structures. H<sub>2</sub>O<sub>2</sub> is dismutated by [[catalase]] to water and [[oxygen]]. H<sub>2</sub>O<sub>2</sub> is produced as a signaling molecule in aerobic metabolism and passes membranes more easily compared to other ROS.
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{{MitoPedia methods
|mitopedia method=Respirometry, Fluorometry
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{{MitoPedia topics
|mitopedia topic=Substrate and metabolite
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== Applications in [[HRR]] ==
=== Measurement of hydrogen peroxide ===
Two techniques to measure H<sub>2</sub>O<sub>2</sub> concentration and H<sub>2</sub>O<sub>2</sub> production can be combined with the O2k:
# [[O2k-Fluorescence LED2-Module|O2k-Fluorometry]] using [[Amplex red]];
# Electrochemical measurement with an amperometric H<sub>2</sub>O<sub>2</sub> sensor.

==== Fluorescence ====

The fluorometric measurement of H<sub>2</sub>O<sub>2</sub> in the O2k is based on the [[O2k-Fluorescence LED2-Module]], using [[Amplex red]] (or one of its brand names).<ref>[[Sumbalova 2011 Abstract Kagoshima|Sumbalova Z, Harrison DK, Gradl P, Fasching M, Gnaiger E (2011) Mitochondrial membrane potential, coupling control, H2O2 production, and the upper limit of mitochondrial performance. Abstract Kagoshima]].</ref>
Please see [[Amplex red]] about the method as well as various application notes: [[MiPNet18.06_Amplex-Yeast]], [[MiPNet18.05_Amplex-Mouse-heart]], [[MiPNet17.17_Amplex-Mouse-brain]].

==== Electrochemical measurement ====

For electrochemically (H<sub>2</sub>O<sub>2</sub> electrode) measuring H<sub>2</sub>O<sub>2</sub> (and all other amperometric methods) please see our [[O2k-NO Amp-Module]]  and its manual [[MiPNet15.05 NO-Manual]]. All stated there about measuring NO is technically also correct for using a H<sub>2</sub>O<sub>2</sub> electrode together with the oxygraph. In this manual you will also find which accessories you need to use a H<sub>2</sub>O<sub>2</sub> electrode together with the O2k-MultiSensor System (there are different requirements for different generations of O2ks). The electrode itself has to be bought from a third party.

It is sometimes stated that the available H<sub>2</sub>O<sub>2</sub> electrodes may not have the required sensitivity for most ROS studies. WPI states a lower detection limit of "<100 nM" for their 2 mm "macro" electrode and "<10 nM" for their 0.1 mm "mini sensor". The latter value is quite similar to the stated detection limit for fluorescence based methods, however it is not clear if the "mini sensor", probable developed for direct tissue insertion, works well in macroscopic chambers.  A direct comparison would be helpful. Please add your experiences!

Picomolar detection ranges have been reported for a method combining Amplex Red (R) with square wave voltammetry.<ref>[[Lyon_2006_Anal_Chem|Lyon J L, Stevenson K J (2006) Picomolar peroxide detection using a chemically activated redox mediator and square wave voltammetry. Anal Chem 78: 8518-8525]]</ref>
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{{#set:Technical service=NO (amperometric) signal |Technical service=Fluorescence }}

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[[Category:technical service]]

=== Reoxygenation of the respiration medium with H<sub>2</sub>O<sub>2</sub> ===

>> [[Re-oxygenation|More detail]]