Pantothenic Acid

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Connected to · 2

cofactor · 2

α-Lipoic Acid
Pyruvate dehydrogenase uses both lipoic acid and coenzyme A: the two-carbon piece cut from pyruvate is handed by the lipoic acid arm to coenzyme A, forming acetyl-CoA, which can then enter the citric acid cycle. Coenzyme A is made from pantothenic acid (B5). The enzyme needs five helper molecules in all and stalls without any one of them.
Fat Types
Vitamin B5 (pantothenic acid) is the raw material for coenzyme A. Whether fatty acids are being built or broken down for fuel, they first have to be attached to coenzyme A before they can be moved and processed.

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A part of coenzyme A

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The name pantothenic acid comes from a Greek word meaning from everywhere: B5 is in almost every food, and a true shortage is extremely rare. Its job in the body is to build an all-purpose carrier called coenzyme A (CoA), which delivers the fragments broken off sugar, fat, and protein to the door of the energy factory.

Think of coenzyme A as a delivery truck. B5 forms most of a long arm on the truck, and at the tip of the arm is a sulfur atom (supplied by cysteine) on which the cargo hangs. Without B5 the arm cannot be fitted: the truck is still there, but it cannot hold anything.

The cargo coenzyme A carries is called an acyl group, and the most important piece is acetyl-CoA. Sugar, fat, and some amino acids all end up as acetyl-CoA when they are broken down, and acetyl-CoA then decides where they go next: into the energy factory to be burned, or off to build new fat and cholesterol. So B5 does not supply energy itself; it is the carrier platform at that crossroads of metabolism.

Watch this step as a mechanism animationOpen mechanism

Educational content, not medical advice — consult a clinician.