1) Amino acid 
Acetyllysine (or acetylated lysine) is an acetyl-derivative of the amino acid lysine. There are multiple forms of acetyllysine - this article refers to N-ε-acetyl-L-lysine. The other form is N-α-acetyl-L-lysine. In proteins, the acetylation of lysine residues is an important mechanism of epigenetics. It functions by regulating the binding of his...