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The reactions related to the urea cycle produce NADH, and NADH can be produced in two different ways. One of these uses oxaloacetate. In the cytosol there are fumarate molecules. Fumarate can be transformed into malate by the actions of the enzyme fumarase. Malate is acted on by malate dehydrogenase to become oxaloacetate, producing a molecule ...
Ketone bodies are water-soluble molecules or compounds that contain the ketone groups produced from fatty acids by the liver (ketogenesis). [1] [2] Ketone bodies are readily transported into tissues outside the liver, where they are converted into acetyl-CoA (acetyl-Coenzyme A) – which then enters the citric acid cycle (Krebs cycle) and is oxidized for energy.
The result is a rate of ketone production higher than the rate of ketone disposal, and a decrease in blood pH. [12] In extreme cases the resulting acetone can be detected in the patient's breath as a faint, sweet odor. There are some health benefits to ketone bodies and ketogenesis as well.
Oxaloacetate is reduced to malate using NADH, a step required for its transportation out of the mitochondria. Malate is oxidized to oxaloacetate using NAD + in the cytosol, where the remaining steps of gluconeogenesis take place. Oxaloacetate is decarboxylated and then phosphorylated to form phosphoenolpyruvate using the enzyme PEPCK.
The ketones are released by the liver into the blood. All cells with mitochondria can take up ketones from the blood and reconvert them into acetyl-CoA, which can then be used as fuel in their citric acid cycles, as no other tissue can divert its oxaloacetate into the gluconeogenic pathway in the way that this can occur in the liver.
Following this, pyruvate is transformed into oxaloacetate, a crucial step in the gluconeogenesis process. [4] It is possible to synthesize glucose from oxaloacetate, ensuring that the blood glucose levels required for the body to produce energy are maintained. In humans, the glucogenic amino acids are: Alanine; Arginine; Asparagine; Aspartic ...
By generating oxaloacetate, it catalyses an important anaplerotic reaction that maintains the citric acid cycle to generate energy by aerobic respiration. [4] Pyruvate carboxylase also plays a role in the formation of the myelin sheath that surrounds certain nerve cells, and the production of neurotransmitters for communication between neurons.
Thus, the two substrates of this enzyme are oxaloacetate and H 2 O, whereas its two products are oxalate and acetate. This enzyme belongs to the family of hydrolases, specifically those acting on carbon-carbon bonds in ketonic substances. The systematic name of this enzyme class is oxaloacetate acetylhydrolase.