Biological implications of acetylation

The simple conversion of an alcohol or phenol into its acetyl (ethanoyl) derivative can have major implications for its biological activity. Probably the best known example is provided by the conversion of morphine into its diethanoate derivative heroin, with a resultant boost to not only the analgesic potency but also the addictive potential. The simplicity of this chemistry ensures that there is a lucrative living to be made turning the raw opium from the poppy fields of Afghanistan into heroin for the streets of almost anywhere in the world. 

A more subtle use of acetylation is seen in the control of gene expression (activity) brought about by the enzymes histone acetyltransferases (HATs) and histone deacetylases (HDACs). One of the undoubted miracles of life is that the entire two-metre long human genome can adopt a more relaxed structure to allow the genes to act as a blueprint for the production of messenger-RNA and ultimately new enzymes and other proteins (ie ranscription).