Coenzyme A


Coenzyme A (CoA), is a coenzyme, has its  role in the synthesis and oxidation of fatty acids, and the oxidation of pyruvate in the citric acid cycle. 

Around 4% of cellular enzymes use it as a substrate. 

CoA biosynthesis requires cysteine, pantothenate (vitamin B5), and adenosine triphosphate (ATP).

In its acetyl form, coenzyme A serves metabolic functions in both the anabolic and catabolic pathways. 

Acetyl-CoA is utilized in the post-translational regulation and allosteric regulation of pyruvate dehydrogenase and carboxylase to maintain and support the partition of pyruvate synthesis and degradation.

Coenzyme A is naturally synthesized from pantothenate, vitamin B5, which is found in food such as meat, vegetables, cereal grains, legumes, eggs, and milk.

Pantothenic acid is an essential vitamin that has a variety of functions: it can be synthesised de novo and is therefore not considered essential. 

Bacteria synthesize pantothenate from the amino acid aspartate and a metabolite in valine biosynthesis.

In all living organisms, coenzyme A is synthesized in a five-step process that requires four molecules of ATP, pantothenate and cysteine.

Coenzyme A is produced commercially via extraction from yeast.

Coenzyme A is, a thiol, it can react with carboxylic acids to form thioesters, thus functioning as an acyl group carrier, which  assists in transferring fatty acids from the cytoplasm to mitochondria. 

A molecule of coenzyme A carrying an acyl group is also referred to as acyl-CoA. 

Coenzyme A  facilitates the production of fatty acids in cells, which are essential in cell membrane structure.

Coenzyme A is one of five crucial coenzymes that are necessary in the reaction mechanism of the citric acid cycle. 

The acetyl-coenzyme A form is the primary input in the citric acid cycle.

Acetyl-coenzyme A is obtained from glycolysis, amino acid metabolism, and fatty acid beta oxidation. 

The citric acid cycle is the body’s primary catabolic pathway and is essential in breaking down the building blocks of the cell such as carbohydrates, amino acids, and lipids.

When there is excess glucose, coenzyme A is used for synthesis of fatty acids.

Acetyl-CoA carboxylase, catalyzes the committed step in fatty acid synthesis. 

Insulin stimulates acetyl-CoA carboxylase, while epinephrine and glucagon inhibit its activity.

During cell starvation, coenzyme A is synthesized and transports fatty acids to the mitochondria. 

Here, acetyl-CoA is generated for oxidation and energy production.

In the citric acid cycle, coenzyme A works is a  regulator in the stimulation of the enzyme pyruvate dehydrogenase.

Protein CoAl plays an important role in regulation of the oxidative stress response. 

Coenzyme A is available as the free acid and lithium or sodium salts. 

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