Hello, How to replace 'M' with 'AME' in coot itself? an option like mutate residue, etc. I couldn't figure out right away so I worked my way around by simply copying AME from one of the pdb from RCSB database and replaced methionine in my model. Linked AME to residue# 2 in coot and refinement was straightforward after generating restraints for the modified model. So it worked for now but still curious as there has to be a way to replace 'M' with 'AME' in coot, isn't it (?). Thanks, Anshul Bhardwaj P.S. Hope it's okay to cross-post on both ccp4bb and phenixbb to get an answer quickly. The information contained in this transmission contains privileged and confidential information. It is intended only for the use of the person named above. If you are not the intended recipient, you are hereby notified that any review, dissemination, distribution or duplication of this communication is strictly prohibited. If you are not the intended recipient, please contact the sender by reply email and destroy all copies of the original message. CAUTION: Intended recipients should NOT use email communication for emergent or urgent health care matters.