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Coenzyme A (CoA, SHCoA, CoASH) is a coenzyme, notable for its role in the synthesis and oxidation of fatty acids, and the oxidation of pyruvate in the citric acid cycle.All genomes sequenced to date encode enzymes that use coenzyme A as a substrate, and around 4% of cellular enzymes use it (or a thioester) as a substrate.
Acetyl-CoA (acetyl coenzyme A) is a molecule that participates in many biochemical reactions in protein, carbohydrate and lipid metabolism. [2] Its main function is to deliver the acetyl group to the citric acid cycle (Krebs cycle) to be oxidized for energy production.
These reactions have different functions in cells. The reaction involving acetyl-CoA and butyrate (EC 2.8.3.8), for example, forms butyrate during fermentation. [3] The reaction involving acetyl-CoA and succinate (EC 2.8.3.18) is part of a modified TCA cycle [4] or forms acetate during fermentation. [5]
General chemical structure of an acyl-CoA, where R is a carboxylic acid side chain. Acyl-CoA is a group of CoA-based coenzymes that metabolize carboxylic acids. Fatty acyl-CoA's are susceptible to beta oxidation, forming, ultimately, acetyl-CoA. The acetyl-CoA enters the citric acid cycle, eventually forming several equivalents of ATP. In this ...
The regioselectivity of this step is essential for the subsequent hydration and oxidation reactions. acyl CoA dehydrogenase: trans-Δ 2-enoyl-CoA Hydration: The next step is the hydration of the bond between C-2 and C-3. The reaction is stereospecific, forming only the L isomer. Hydroxyl group is positioned suitable for the subsequent oxidation ...
The sole carbon feed stock of the pathway is acetyl-CoA. The first step condenses two acetyl-CoA molecules to yield acetoacetyl-CoA. This is followed by a second condensation to form HMG-CoA (3-hydroxy-3- methyl-glutaryl-CoA). Reduction of HMG-CoA yields (R)-mevalonate. These first 3 enzymatic steps are called the upper mevalonate pathway. [4]
Structure of acetyl coenzyme A, a thioester that is a key intermediate in the biosynthesis of many biomolecules. Thioesters are common intermediates in many biosynthetic reactions, including the formation and degradation of fatty acids and mevalonate , precursor to steroids.
The reaction catalyzed by acetyl-CoA synthetase takes place in two steps. First, AMP must be bound by the enzyme to cause a conformational change in the active site, which allows the reaction to take place. The active site is referred to as the A-cluster. [4]