The opening motion of the catalytic domain. Left panel: The structure of the CD is composed of three groups of canonical β-sheets arranged in a triangular fashion with a group of two β-sheets closely neighbouring a conserved α-helix defining a cleft for the binding of the lysine-histone ligand. The cofactor SAM binds in a cavity adjacent to the CD connected through a channel. The flexible regulatory loop is shown in red. The motion of the regulatory loop is indicated with bent black closed arrows. Right panel: Model of the NSD-CDs bound with the H3-peptide (a.a. 32–38) after MD simulations. H3K36 is indicated by an arrow. The electrostatic surface is colored as follows: blue: positive charges; red: negative charges with unit +5/-5 kb.T.ec−1.