Respiratory complex II (succinate:ubiquinone oxidoreductase) connects the tricarboxylic acid cycle to the electron transport chain in mitochondria and many prokaryotes. Complex II mutations have been linked to neurodegenerative diseases and metabolic defects in cancer. However, there is no convenient stoichiometric assay for the catalytic activity of complex II. Here, we present a simple, quantitative, real-time method to detect the production of fumarate from succinate by complex II that is easy to implement and applicable to the isolated enzyme, membrane preparations, and tissue homogenates. Our assay uses fumarate hydratase to convert fumarate to malate and uses oxaloacetate decarboxylating malic dehydrogenase to convert malate to pyruvate and to convert NADP+ to NADPH; the NADPH is detected spectrometrically. Simple protocols for the high-yield production of the two enzymes required are described; oxaloacetate decarboxylating malic dehydrogenase is also suitable for accurate determination of the activity of fumarate hydratase. Unlike existing spectrometric assay methods for complex II that rely on artificial electron acceptors (e.g., 2,6-dichlorophenolindophenol), our coupled assay is specific and stoichiometric (1:1 for succinate oxidation to NADPH formation), so it is suitable for comprehensive analyses of the catalysis and inhibition of succinate dehydrogenase activities in samples with both simple and complex compositions.
A spectrophotometric coupled enzyme assay to measure the activity of succinate dehydrogenase☆
Published 2013 in Analytical Biochemistry
ABSTRACT
PUBLICATION RECORD
- Publication year
2013
- Venue
Analytical Biochemistry
- Publication date
2013-11-01
- Fields of study
Biology, Medicine, Chemistry
- Identifiers
- External record
- Source metadata
Semantic Scholar, PubMed
CITATION MAP
EXTRACTION MAP
CLAIMS
CONCEPTS
- coupled enzyme assay
A multi-enzyme assay format that converts the target reaction product into a spectrometrically detectable signal.
Aliases: coupled assay
- fumarate hydratase
An enzyme that converts fumarate to malate as the first coupling step in the assay.
Aliases: fumarase
- nadph spectrometric detection
The optical measurement of NADPH formation used as the assay signal.
Aliases: NADPH readout, spectrophotometric readout
- oxaloacetate decarboxylating malic dehydrogenase
An enzyme used to convert malate to pyruvate while reducing NADP+ to NADPH in the assay.
Aliases: malic dehydrogenase, MDH
- succinate dehydrogenase
Respiratory complex II enzyme activity that oxidizes succinate to fumarate in the assay context.
Aliases: complex II, succinate:ubiquinone oxidoreductase
REFERENCES
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