text: Deacylations "play crucial roles in gene transcription and most likely in all eukaryotic biological processes that involve chromatin".
  Acetylation is one type of post-translational modification of proteins.  The acetylation of the ε-amino group of lysine, which is common, converts a charged side chain to a neutral one.  Acetylation/deacetylation of histones also plays a role in gene expression and cancer.  These modifications are effected by enzymes called histone acetyltransferases (HATs) and histone deacetylases (HDACs). 
  Two general mechanisms are known for deacetylation.  One mechanism involves zinc binding to the acetyl oxygen.  Another family of deacetylases require NAD, which transfers an ribosyl group to the acetyl oxygen.