Dear Developers, I did phosphorylation of amino acid in protein, then I was about to do energy minimization using Chimera MINIMIZE STRUCTURE module, but it is throwing the error ( I mentioned below ). **************************************************** Running PARMCHK for PP.pdb Using main parameter file parm10.dat modified by heme-iron.frcmod, frcmod.ff14SB, frcmod.ionsjc_tip3p *Chimera/MMTK cannot minimize structure, probably because there is no parameter for ''No parameters for bond Atom 0.TPO_144__0_0_1_145.N (atom type n) - Atom 0.GLN_143__0_0_1_144.peptide.C (atom type C)''* ********************************************** *Please help me to sort out the issue.* I also tried to do phosphorylate using Chimera, even that structure also getting the same error while doing energy minimization. -- *Have a nice day,* Thanks & Regards, *SELVA BABU S* M.Sc Scholar (Bioinformatics) *TNAU, Coimbatore*