AskDefine | Define acetyl

Dictionary Definition

acetyl n : the organic group of acetic acid (CH3CO-) [syn: acetyl group, acetyl radical, ethanoyl group, ethanoyl radical]

User Contributed Dictionary



From acētum "vinegar" + (hylē) "substance".


  1. The univalent radical CH3CO- derived from acetic acid.

Extensive Definition

In organic chemistry, acetyl (ethanoyl), is a functional group, the acyl of acetic acid, with chemical formula -COCH3. It is sometimes abbreviated as Ac (not to be confused with the element actinium). The acetyl radical contains a methyl group single-bonded to a carbonyl. The carbon of the carbonyl has a lone electron available, with which it forms a chemical bond to the remainder R of the molecule.
The acetyl radical is a component of many organic compounds, including the neurotransmitter acetylcholine, and acetyl-CoA, and the analgesics acetaminophen and acetylsalicylic acid (better known as aspirin).


The introduction of an acetyl group into a molecule is called acetylation (or ethanoylation). In biological organisms, acetyl groups are commonly transferred bound to Coenzyme A (CoA), in the form of acetyl-CoA. Acetyl-CoA is an important intermediate both in the biological synthesis and in the breakdown of many organic molecules.
Acetyl groups are also frequently added to histones and other proteins modifying their properties. For example, on the DNA level, histone acetylation by acetyltransferases (HATs) causes an expansion of chromatin architecture allowing for genetic transcription to take place. Conversely, removal of the acetyl group by histone deacetylases (HDACs) condenses DNA structure, thereby preventing transcription.
Chemical acetylation can be achieved using a variety of methods, most commonly by the use of acetic anhydride or acetyl chloride in the presence of a tertiary or aromatic amine base.


When acetyl groups are bound to certain other organic molecules, they impart an increased ability to cross the blood-brain barrier. This makes the drug reach the brain more quickly, making the drug's effects more intense and increasing the effectiveness of a given dose. Acetyl groups are used to make the natural anti-inflammatant salicylic acid into the more effective acetylsalicylic acid, or aspirin. Similarly, they make the natural painkiller morphine into diacetylmorphine, or heroin.


See also

acetyl in Danish: Acetyl
acetyl in German: Acetylgruppe
acetyl in French: Acétyle
acetyl in Hungarian: Acetilcsoport
acetyl in Dutch: Acetyl
acetyl in Japanese: アセチル基
acetyl in Norwegian Bokmål: Acetyl
acetyl in Norwegian Nynorsk: Acetyl
acetyl in Polish: Grupa acetylowa
acetyl in Portuguese: Acetila
acetyl in Swedish: Acetyl
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