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Oxaloacetate + 2 H + + 2 e − → Malate-0.17 [10] While under standard conditions malate cannot reduce the more electronegative NAD +:NADH couple, in the cell the concentration of oxaloacetate is kept low enough that Malate dehydrogenase can reduce NAD + to NADH during the citric acid cycle. Fumarate + 2 H + + 2 e − → Succinate +0.03 [9]
Malate is acted on by malate dehydrogenase to become oxaloacetate, producing a molecule of NADH. After that, oxaloacetate will be recycled to aspartate, as transaminases prefer these keto acids over the others. This recycling maintains the flow of nitrogen into the cell. Relationship of oxaloacetic acid, malic acid, and aspartic acid
The reaction it catalyzes is: pyruvate + HCO − 3 + ATP → oxaloacetate + ADP + P. It is an important anaplerotic reaction that creates oxaloacetate from pyruvate. PC contains a biotin prosthetic group [1] and is typically localized to the mitochondria in eukaryotes with exceptions to some fungal species such as Aspergillus nidulans which have a cytosolic PC.
1. CO 2 is fixed to produce a four-carbon molecule (malate or aspartate). 2. The molecule exits the cell and enters the bundle sheath cells. 3. It is then broken down into CO 2 and pyruvate. CO 2 enters the Calvin cycle to produce carbohydrates. 4. Pyruvate reenters the mesophyll cell, where it is reused to produce malate or aspartate.
Malate, in the mitochondrial matrix, can be used to make pyruvate (catalyzed by malic enzyme) or oxaloacetic acid, both of which can enter the citric acid cycle. Glutamine can also be used to produce oxaloacetate during anaplerotic reactions in various cell types through "glutaminolysis", which is also seen in many c-Myc transformed cells. [ 3 ]
In enzymology, a malate dehydrogenase (oxaloacetate-decarboxylating) (EC 1.1.1.38) is an enzyme that catalyzes the chemical reaction below (S)-malate + NAD + pyruvate + CO 2 + NADH. Thus, the two substrates of this enzyme are (S)-malate and NAD +, whereas its 3 products are pyruvate, CO 2, and NADH.
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Plants that use the C 4 carbon fixation process chemically fix carbon dioxide in the cells of the mesophyll by adding it to the three-carbon molecule phosphoenolpyruvate (PEP), a reaction catalyzed by an enzyme called PEP carboxylase, creating the four-carbon organic acid oxaloacetic acid. Oxaloacetic acid or malate synthesized by this process ...