Dear All I am planning to purify monoclonal antibody. In this concern I found Pseudospecific ligands such as histidine, tryptophan,phenylalanine etc. can be used to purify a wide range of bio-molecules and especially immunoglobulin. I wish to know the structural mode of binding of Histidine (as affinity ligand) with Immunoglobulin. Sanjit Kumar