Acetylcarnitine

1

**Acetyl-L-carnitine**, **ALCAR** or **ALC**, is an acetylated form of L-carnitine. It is naturally produced by the human body, and it is available as a dietary supplement. Acetylcarnitine is broken down in the blood by plasma esterases to carnitine which is used by the body to transport fatty acids into the mitochondria for breakdown.

**O-acetylcarnitine** is an O-acylcarnitine having acetyl as the acyl substituent. It has a role as a human metabolite. It derives from an acetic acid. It is a conjugate base of an O-acetylcarnitinium.

## Biochemical production and action

Carnitine is both a nutrient and made by the body as needed; it serves as a substrate for important reactions in which it accepts and gives up an acyl group. Acetylcarnitine is the most abundant naturally occurring derivative and is formed in the reaction:

acetyl-CoA + carnitine ⇌ CoA + acetylcarnitine
where the acetyl group displaces the hydrogen atom in the central hydroxyl group of carnitine. Coenzyme A (CoA) plays a key role in the Krebs cycle in mitochondria, which is essential for the production of ATP, which powers many reactions in cells; acetyl-CoA is the primary substrate for the Krebs cycle, once it is de-acetylated, it must be re-charged with an acetyl-group in order for the Krebs cycle to keep working.

Most cell types appear to have transporters to import carnitine and export acyl-carnitines, which seems to be a mechanism to dispose of longer-chain moieties; however many cell types can also import ALCAR.

Within cells, carnitine plays a key roles in importing acyl-CoA into mitochondria; the acyl-group of the acyl-CoA is transferred to carnitine, and the acyl-carnitine is imported through both mitochondrial membranes before being transferred to a CoA molecule, which is then beta oxidized to acetyl-CoA. A separate set of enzymes and transporters also plays a buffering role by eliminating acetyl-CoA from inside mitochondria created by the pyruvate dehydrogenase complex that is in excess of its utilization by the Krebs cycle; carnitine accepts the acetyl moiety and becomes ALCAR, which is then transported out of the mitochondria and into the cytosol, leaving free CoA inside the mitochondria ready to accept new import of fatty acid chains. ALCAR in the cytosol can also form a pool of acetyl-groups for CoA, should the cell need it.

Excess acetyl-CoA causes more carbohydrates to be used for energy at the expense of fatty acids. This occurs by different mechanisms inside and outside the mitochondria. ALCAR transport decreases acetyl-CoA inside the mitochondria, but increases it outside.

## Molview instructions

first, build a cyclohexane and cut half of it off, add three carbon bonds attaching to it, with a nitrogen in the middle, charge the nitrogen with a positive charge, then add and oxygen and then an acetic acid-like figure attaching to the oxygen, then add another acetic acid figure on the carbon in the southern part of the atom, with another oxygen at the southern end, charge the oxygen with a negative charge, and it should look like this:

## Appearance

It has 17 Hydrogen atoms, 9 Carbon atoms, 1 Nitrogen atom, and 4 Oxygen atoms.

## Pubchem CID

it is the first compound to be listed in PubChem (numberwise), as it has the CID 1

For the SMILES, use CC(=O)OC(CC(=O)[O-])C[N+](C)(C)C.

## Trivia

* It is the first compound on PubChem to be listed numberwise, in accordance to numerical order from 1 to infinity.

## External Links

Acetylcarnitine on PubChem

Acetylcarnitine on MolView

Acetylcarnitine on Wikipedia