Dear phenixbb, i have a protein on which a cysteine has been modified and I can't find a way to refine my structure with it. this seams like a fairly easy problem as a lot of people are refining structures with post-translational modifications, but i can't find the info on how to do it. Could someone point me to a web page explaining it? If i understand correctly, i have to create the modified residue, create the restraints, and define it as a L-peptide. Is that correct? thanks a lot vincent -- Vincent Chaptal Dept. of Physiology at UCLA http://www.physiology.ucla.edu/Labs/Abramson/index.html http://www.physiology.ucla.edu/Labs/Abramson/index.html/ Phone: 1-310-206-1399 IMPORTANT WARNING: This email (and any attachments) is only intended for the use of the person or entity to which it is addressed, and may contain information that is privileged and confidential. You, the recipient, are obligated to maintain it in a safe, secure and confidential manner. Unauthorized redisclosure or failure to maintain confidentiality may subject you to federal and state penalties. If you are not the intended recipient, please immediately notify us by return email, and delete this message from your computer.