Search results
Results From The WOW.Com Content Network
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.
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.
In IUPAC nomenclature, an acetyl group is called an ethanoyl group. An acetyl group contains a methyl group (−CH 3) that is single-bonded to a carbonyl (C=O), making it an acyl group. The carbonyl center of an acyl radical has one non-bonded electron with which it forms a chemical bond to the remainder (denoted with the letter R) of the molecule.
The systematic name of this enzyme class is acetyl-CoA:[acyl-carrier-protein] S-acetyltransferase. Other names in common use include acetyl coenzyme A-acyl-carrier-protein transacylase, acetyl-CoA:ACP transacylase, [acyl-carrier-protein]acetyltransferase, [ACP]acetyltransferase, and ACAT. This enzyme participates in fatty acid biosynthesis.
Acetyl Co-A can also be used in fatty acid synthesis, and a common function of the synthetase is to produce acetyl Co-A for this purpose. [3] 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 4 substrates of this enzyme are acetyl-CoA, malonyl-CoA, NADPH, and H +, whereas its 4 products are acyl-CoA, CoA, CO 2, and NADP +. More specifically, the FAS catalysis mechanism consumes an acetyl coenzyme A ( acetyl-CoA ) and seven malonyl-CoA molecules to produce a palmitoyl-CoA .
Two specific enzymes participate on the carbon monoxide side of the pathway: CO dehydrogenase and acetyl-CoA synthase. The former catalyzes the reduction of the CO 2 and the latter combines the resulting CO with a methyl group to give acetyl-CoA. [1] [2] Some anaerobic bacteria use the Wood–Ljungdahl pathway in reverse to break down acetate.
A proposed mechanism is the release of CO 2 from biotin, which subsequently abstracts a proton from the methyl group from acetyl-CoA carboxylase. The resulting enolate attacks CO 2 to form malonyl-CoA. In a competing mechanism, proton abstraction is concerted with the attack of acetyl-CoA.