I would like to perform docking with Autodock4.2.6. Before docking I would like to optimise the crystallized PDB structure by adding missing residues. How do I add missing residues by swissPDBviewer? I have 2 missing residues in the N terminal and one missing residue in the C terminal. How do I know the protonation state of Histidine residues? Is histidine should be protonated before docking?