Pantothenic acid is an important cofactor of CoA and is essential for the completion of biologic acetylation reactions, as illustrated by the formation of sulfonamide in the liver and choline in the brain. The structure of pantothenic acid is shown in Figure 7.5.
Pantothenic acid is ingested in its CoA form and is then hydrolyzed in the intestine to pantothenic acid, which is then absorbed into the bloodstream. Pantoth-enate containing CoA is essential for the maintenance of the respiratory TCA cycle, fatty acid synthesis, and the degradation of a variety of other compounds. All of the enzymes required for CoA synthesis are present in cell cytoplasm. Mitochondria are the final site of CoA synthesis, because 95% of CoA is found in mitochondria, and CoA does not cross the mitochondria membranes. Multiple hydrolytic steps liberate pantothenic acid from CoA and allow for it to eventually be excreted in the urine. Pantothenic acid has also been shown to be required for the synthesis of key amino acids (methionine, leucine, and arginine).3
Pantothenic acid deficiencies are rare in humans, because this vitamin is found in so many sources of our diet. Severe malnutrition leads to pantothenic acid deficiency with symptoms that include painful burning sensations in the feet and ch3 oh o o
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