Acylation
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(′as·ə′lā·shən)
(organic chemistry) Any process whereby the acyl group is incorporated into a molecule by substitution.
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A process in which a hydrogen atom in an organic compound is replaced by an acyl group (RCO, where R = an organic group). The reaction involves substitution by a nucleophile (electron donor) at the electrophilic carbonyl group (C&dbnd;O) of a carboxylic acid derivative. The substitution usually proceeds by an addition-elimination sequence. Two common reagents, with the general formula RCOX, that bring about acylation are acid halides (X = Cl, Br) and anhydrides (X = OCOR). There are also other acylating reagents. The carboxylic acid (X = OH) itself can function as an acylating agent when it is protonated by a strong acid catalyst as in the direct esterification of an alcohol. Typical nucleophiles in the acylation reaction are alcohols (ROH) or phenols (ArOH), both of which give rise to esters, and ammonia or amines (RNH2), which give amides. See also Acid anhydride; Acid halide; Amide; Amine; Electrophilic and nucleophilic reagents.
Oxford Dictionary of Biochemistry:
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acylation
the process of introducing an acyl group into a compound by substitution for a hydrogen atom.
—acylated adj.
| acyl-CoA reductase, acyl-CoA dehydrogenase, acyl-CoA | |
| acylglycerol, acylphosphatase, acyltransferase |
Saunders Veterinary Dictionary:
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acylation
Introduction of an acyl radical into the molecules of a compound.
Wikipedia on Answers.com:
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Acylation
In chemistry, acylation (rarely, but more formally: alkanoylation) is the process of adding an acyl group to a compound. The compound providing the acyl group is called the acylating agent.
Because they form a strong electrophile when treated with some metal catalysts, acyl halides are commonly used as acylating agents. For example, Friedel-Crafts acylation uses acetyl chloride (ethanoyl chloride), CH3COCl, as the agent and aluminum chloride (AlCl3) as a catalyst to add an ethanoyl (acetyl) group to benzene:
The mechanism of this reaction is electrophilic substitution.
Acyl halides and anhydrides of carboxylic acids are also commonly used acylating agents to acylate amines to form amides or acylate alcohols to form esters. The amines and alcohols are nucleophiles; the mechanism is nucleophilic addition-elimination. Succinic acid is also commonly used in a specific type of acylation called succination. Oversuccination occurs when more than one succinate adds to a single compound.
Acylation in biology
Protein acylation is the post-translational modification of proteins via the attachment of functional groups through acyl linkages. One prominent type is fatty acylation, the addition of fatty acids to particular amino acids (e.g. myristoylation or palmitoylation).[1] Protein acylation has been observed as a mechanism of biological signaling.[2]
See also
References
- ^ Resh, M. D. (1999). "Fatty acylation of proteins: New insights into membrane targeting of myristoylated and palmitoylated proteins". Biochimica et Biophysica Acta 1451 (1): 1–16. doi:10.1016/S0167-4889(99)00075-0. PMID 10446384.
- ^ Towler, D A; Gordon, J I; Adams, S P; Glaser, L (1988). "The Biology and Enzymology of Eukaryotic Protein Acylation". Annual Review of Biochemistry 57 (1): 69–97. doi:10.1146/annurev.bi.57.070188.000441.
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