I work on a particular kinase molecule and would like to know whether it is possible to phosphorylate it at tyrosine residues using Pymol tool. I know for some residues like Ser/Thr it is possible to change to Glu/Asp. But for Tyr getting an active mutant is difficult. So is it possible to add do some manipulations using Pymol to add phospho group to the Tyr residues ?