Question (75851) | MitoTox™ Complex V OXPHOS Activity Assay Kit (ab109907)

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Question

I am looking for Complex I-IV activity kits to study in vitro activity inhibitors after incubating mouse, rat, and human cells with the inhibitors prior to mitochondrial extraction. I am worried that either the kit will not detect the inhibited portion of the mechanism (such as ab109721 not being affected by rotenone since it detects the dehyrogenase activity and not the ubiquinone activity which is affected by rotenone) or the inhibitory affect will be reversed following mitochondrial extraction and sample preparation. Do you have any advice or specific product recommendations?

Answer

The kits that are the best suited for your experiment are listed below. I am having our datasheets team update the species reactivity.
ab109903, Complex I; reactivity = Human, mouse, rat, bovine
https://www.abcam.com/mitotox%E2%84%A2-complex-i-oxphos-activity-microplate-assay-ab109903.html
ab109904, Complex II, reactivity = Human, mouse and bovine
https://www.abcam.com/mitotox%E2%84%A2-complex-ii-oxphos-activity-microplate-assay-ab109904.html
ab109905, Complex II + III, reactivity = This is an in solution assay so it will work with mitochondria from any species, provided that the mitochondria is of good quality. It will not work with homogenate – it requires purified mitochondria
https://www.abcam.com/mitotoxtrade-complex-ii-nbsp-iii-oxphos-activity-microplate-assay-ab109905.html
ab109906, Complex IV, reactivity = Human and bovine
https://www.abcam.com/mitotoxtrade-complex-iv-oxphos-activity-microplate-assay-ab109906.html
ab109907, Complex V, reactivity = Human, mouse, rat and bovine.
https://www.abcam.com/mitotoxtrade-complex-v-oxphos-activity-microplate-assay-ab109907.html

ab110419, Complexes I - V (contains the five kits above at a discounted price)
https://www.abcam.com/mitotox%E2%84%A2-complete-oxphos-activity-assay-kit-5-assays-ab110419.html
In regards to inhibitor treatment, the laboratory agrees that the effects would be reversible. See their response and recommendations below:

If you were to treat the cells with for example rotenone, then isolate the mitochondria from rotenone treated cells, this will wash off all the rotenone from the sample during the sample prep and would simply find no inhibition detected by the assay.

What we would recommend is to test normal mitochondria in-vitro with the inhibitor compound as it is suggested in the kit protocols above.
The kits have a bovine heart mitochondria control, which you can use to see how the assay works (creating a positive and negative control with BHM plus or minus inhibitors).

Then you can compare the BHM results with the results obtained with the mitochondria prepared from your cell system.
The compound inhibitor must be present during the activity assay, otherwise the data will not reflect the immediate in vitro inhibitory effect of the compound, but more likely the downstream effect of that compound (i.e. If the compound generates as a downstream effect oxidative stress and this in turn affects the activity of one of the complexes of the electron transport chain).