What is pyruvate carboxylase regulated by?
Pyruvate carboxylase is allosterically regulated by acetyl-CoA, Mg-ATP, and pyruvate.
What is the function of phosphoenolpyruvate carboxykinase?
Phosphoenolpyruvate carboxykinase (PEPCK) is an enzyme in the lyase family used in the metabolic pathway of gluconeogenesis. It converts oxaloacetate into phosphoenolpyruvate and carbon dioxide. It is found in two forms, cytosolic and mitochondrial.
How does acetyl-CoA regulate pyruvate carboxylase?
More specifically pyruvate carboxylase is activated by acetyl-CoA. Because acetyl-CoA is an important metabolite in the TCA cycle which produces a lot of energy, when concentrations of acetyl-CoA are high organisms use pyruvate carboxylase to channel pyruvate away from the TCA cycle.
How does regulation of pyruvate carboxylase impact gluconeogenesis?
Pyruvate carboxylase is a multisubunit enzyme that has acetyl CoA as a positive allosteric regulator. The enzyme is critical for both gluconeogenesis and fatty acid synthesis, since it replenishes the citric acid cycle intermediates (malate or citrate) that leave the mitochondria as part of biosynthetic processes.
What reaction is catalyzed by pyruvate carboxylase?
Pyruvate carboxylase (PC) is a mitochondrial enzyme bound to biotin that catalyzes the conversion of pyruvate to oxaloacetate when abundant acetyl CoA is available, replenishing Krebs cycle intermediates in the mitochondrial matrix.
How is PEPCK regulated?
Acute regulation of PEPCK is achieved by modulating transcription of the gene, which is tightly regulated by cAMP (the mediator of glucagon and catecholamines), glucocorticoids and insulin.
Why is PEPCK important?
PEPCK should be viewed as a cataplerotic enzyme because it plays the important role of removing citric acid cycle anions for either the biosynthetic process or the subsequent complete oxidation of the these compounds to carbon dioxide in the citric acid cycle.
How is oxaloacetate regulated?
The regulation of the supply of oxaloacetate (OAA) for mitochondrial metabolism via phosphoenolpyruvate carboxylase (PEPC) by metabolites is studied in barley (Hordeum vulgare L.) leaf protoplasts in light or darkness as well as under photorespiratory or non-photorespiratory conditions.
What is the role of oxaloacetate?
Biochemical functions. Oxaloacetate is an intermediate of the citric acid cycle, where it reacts with acetyl-CoA to form citrate, catalyzed by citrate synthase. It is also involved in gluconeogenesis, the urea cycle, the glyoxylate cycle, amino acid synthesis, and fatty acid synthesis.
Is acetyl-CoA an allosteric activator of pyruvate carboxylase?
The activity of the biotin-dependent enzyme pyruvate carboxylase from many organisms is highly regulated by the allosteric activator acetyl-CoA. A number of X-ray crystallographic structures of the native pyruvate carboxylase tetramer are now available for the enzyme from Rhizobium etli and Staphylococcus aureus.