Miwa 2015 Free Radic Biol Med

Miwa S, Treumann A, Bell A, Vistoli G, Nelson G, Hay S, von Zglinicki T (2015) Carboxylesterase converts Amplex red to resorufin: Implications for mitochondrial H2O2 release assays.. Free Radic Biol Med 90:173-83.

» PMID: 26577176 Open Access

Miwa S, Treumann A, Bell A, Vistoli G, Nelson G, Hay S, von Zglinicki T (2015) Free Radic Biol Med

Abstract: Amplex Red is a fluorescent probe that is widely used to detect hydrogen peroxide (H₂O₂) in a reaction where it is oxidised to resorufin by horseradish peroxidase (HRP) as a catalyst. This assay is highly rated amongst other similar probes thanks to its superior sensitivity and stability. However, we report here that Amplex Red is readily converted to resorufin by a carboxylesterase without requiring H₂O₂, horseradish peroxidase or oxygen: this reaction is seen in various tissue samples such as liver and kidney as well as in cultured cells, causing a serious distortion of H₂O₂ measurements. The reaction can be inhibited by Phenylmethyl sulfonyl fluoride (PMSF) at concentrations which do not disturb mitochondrial function nor the ability of the Amplex Red-HRP system to detect H₂O₂. In vitro experiments and in silico docking simulations indicate that carboxylesterases 1 and 2 recognise Amplex Red with the same kinetics as carboxylesterase-containing mitochondria. We propose two different approaches to correct for this problem and re-evaluate the commonly performed experimental procedure for the detection of H₂O₂ release from isolated liver mitochondria. Our results call for a serious re-examination of previous data. • Keywords: Amplex Red, Mitochondria, Liver, Reactive Oxygen Species, Measurement, Carboxylesterase

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Labels: MiParea: Respiration, Pharmacology;toxicology 

Stress:Oxidative stress;RONS  Organism: Mouse  Tissue;cell: Liver  Preparation: Isolated mitochondria 

Coupling state: LEAK, OXPHOS, ET  Pathway: N, S, ROX  HRR: Oxygraph-2k