Oxaloacetate
Oxaloacetate - Related Videos
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This video describes a colorimetric assay to measure the mitochondrial citrate synthase activity assay present in the tissue homogenate of Drosophila.
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The citric acid cycle, also known as the Krebs cycle or TCA cycle, consists of several energy-generating reactions that yield one ATP molecule, three NADH molecules, one FADH2 molecule, and two CO2 molecules. Acetyl CoA is the point-of-entry into the citric acid cycle, which occurs in the inner membrane (i.e., matrix) of mitochondria in eukaryotic cells or the cytoplasm of prokaryotic cells. Prior to the citric acid cycle, pyruvate oxidation produced two acetyl CoA molecules per glucose...
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An Introduction to Cell Metabolism
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In cells, critical molecules are either built by joining together individual units like amino acids or nucleotides, or broken down into smaller components. Respectively, the reactions responsible for this are referred to as anabolic and catabolic. These reactions require or produce energy typically in the form of a “high-energy” molecule called ATP. Together, these processes make up “Cell Metabolism,” and are hallmarks of healthy, living cells.JoVE’s introduction to cell metabolism briefly...
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A Screenable In Vivo Assay for Mitochondrial Modulators Using Transgenic Bioluminescent Caenorhabditis elegans
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A protocol is described for in vivo detection of effects of mitochondrial inhibitors in the model organism Caenorhabditis elegans and for identification of potential enhancing compounds. This protocol can be used to screen drug libraries for compounds modulating mitochondrial function.
FAQs
Oxaloacetate reacts with acetyl-CoA in a citrate synthase-catalyzed condensation, producing citrate and initiating another cycle turn. This reaction brings a two-carbon acetyl group into a pathway built around a four-carbon acceptor. Subsequent reactions process the resulting citrate, release carbon dioxide, generate reducing equivalents, and ultimately restore oxaloacetate for continued cycling.
The amount of oxaloacetate affects how readily acetyl-CoA can enter the citric acid cycle through citrate formation. Consequently, changes in its abundance can alter cycle flux, meaning the overall movement of metabolites through the pathway. This makes oxaloacetate important for understanding how cells adjust respiration when carbon availability or metabolic demands change.
Oxaloacetate supports respiration by accepting acetyl-CoA at the start of the citric acid cycle, yet it also contributes carbon to biosynthesis. Its availability can therefore influence whether cellular carbon remains associated with energy production or is redirected toward products such as amino acids or glucose formed through gluconeogenesis. This dual role links energy generation with carbon allocation.
Within the citric acid cycle, oxaloacetate is regenerated after carbon dioxide release and reducing-equivalent production, allowing the pathway to continue. In gluconeogenesis, it serves instead as a precursor for glucose synthesis. The same intermediate can therefore support repeated respiratory cycling or provide carbon for biosynthesis, depending on the cell's metabolic requirements.
Examining oxaloacetate helps researchers connect several aspects of metabolism rather than viewing respiration in isolation. Its relationship to citrate formation, cycle regeneration, amino acid synthesis, and gluconeogenesis reveals how cells coordinate energy production with carbon allocation. Because its abundance influences cycle flux, oxaloacetate also provides context for studying metabolic adaptation in health and disease.
A useful conceptual analysis follows oxaloacetate through its entry reaction with acetyl-CoA, the downstream release of carbon dioxide and generation of reducing equivalents, and its eventual regeneration. Researchers can then consider whether the intermediate is also being used for amino acid synthesis or gluconeogenesis. This framework links pathway continuity with competing biosynthetic demands.
Oxaloacetate provides a point of comparison because it participates in both central respiration and precursor formation. When its abundance changes, the balance between citric acid cycle activity and carbon use for amino acid synthesis or gluconeogenesis may also change. Studying this relationship helps explain how cells adapt metabolism to different demands without separating energy production from biosynthesis.