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In this reaction the glutamate is converted into alpha-ketoglutarate, which is a citric acid cycle intermediate. The intermediates that can provide the carbon skeletons for amino acid synthesis are oxaloacetate which forms aspartate and asparagine ; and alpha-ketoglutarate which forms glutamine , proline , and arginine .
In this cycle, the enzyme isocitrate dehydrogenase 3 converts isocitrate (isocitrate has 4 isomers of which only the (−)-d-threo-isomer is the naturally occurring isomer in the citric acid cycle. [13]) to α-ketoglutarate which in the next step is converted to succinyl-CoA by the oxoglutarate dehydrogenase complex of enzymes.
Oxoglutarate dehydrogenase is a key control point in the citric acid cycle. It is inhibited by its products, succinyl CoA and NADH. A high energy charge in the cell will also be inhibitive. ADP and calcium ions are allosteric activators of the enzyme.
The α-ketoglutarate family of amino acid synthesis (synthesis of glutamate, glutamine, proline and arginine) begins with α-ketoglutarate, an intermediate in the Citric Acid Cycle. The concentration of α-ketoglutarate is dependent on the activity and metabolism within the cell along with the regulation of enzymatic activity.
The conversion of the amino acid glutamine to α-ketoglutarate takes place in two reaction steps: Conversion of glutamine to α-ketoglutarate. 1. Hydrolysis of the amino group of glutamine yielding glutamate and ammonium. Catalyzing enzyme: glutaminase (EC 3.5.1.2) 2. Glutamate can be excreted or can be further metabolized to α-ketoglutarate.
Isocitrate dehydrogenase (IDH) (EC 1.1.1.42) and (EC 1.1.1.41) is an enzyme that catalyzes the oxidative decarboxylation of isocitrate, producing alpha-ketoglutarate (α-ketoglutarate) and CO 2. This is a two-step process, which involves oxidation of isocitrate (a secondary alcohol ) to oxalosuccinate (a ketone ), followed by the ...
In organic chemistry, keto acids or ketoacids (also called oxo acids or oxoacids) are organic compounds that contain a carboxylic acid group (−COOH) and a ketone group (>C=O). [1] In several cases, the keto group is hydrated. The alpha-keto acids are especially important in biology as they are involved in the Krebs citric acid cycle and in ...
This gene encodes a subunit that catalyzes the oxidative decarboxylation of alpha-ketoglutarate to Succinyl-CoA at its active site in the fourth step of the citric acid cycle by acting as a base to facilitate the decarboxylation. The main residues responsible for the catalysis are thought to be His 260, Phe 227, Gln685, His 729, Ser302, and His ...