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Oxaloacetic acid (also known as oxalacetic acid or OAA) is a crystalline organic compound with the chemical formula HO 2 CC(O)CH 2 CO 2 H. Oxaloacetic acid, in the form of its conjugate base oxaloacetate, is a metabolic intermediate in many processes that occur in animals.
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]
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.
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.
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 ]
After malate reaches the mitochondrial matrix, it is converted by mitochondrial malate dehydrogenase into oxaloacetate, during which NAD + is reduced with two electrons to form NADH. Oxaloacetate is then transformed into aspartate (since oxaloacetate cannot be transported into the cytosol) by mitochondrial aspartate aminotransferase.
Glyoxylate condenses with acetyl-CoA (a step catalyzed by malate synthase), yielding malate. Both malate and oxaloacetate can be converted into phosphoenolpyruvate, which is the product of phosphoenolpyruvate carboxykinase, the first enzyme in gluconeogenesis. The net result of the glyoxylate cycle is therefore the production of glucose from ...
Phosphoenolpyruvate carboxylase (also known as PEP carboxylase, PEPCase, or PEPC; EC 4.1.1.31, PDB ID: 3ZGE) is an enzyme in the family of carboxy-lyases found in plants and some bacteria that catalyzes the addition of bicarbonate (HCO 3 −) to phosphoenolpyruvate (PEP) to form the four-carbon compound oxaloacetate and inorganic phosphate: [1]