Hello All, I would like to restrain the positions of ribose/phosphate atoms of altloc 'A' to the positions of those in altloc 'B'. Problem is, altloc A and altloc B are different residue types, so phenix.refine exits stating that there are no common atoms when I enter the following NCS-type restraint: selection: chain I and altloc A and resid 1 and (phosphate or ribose) restrain: chain I and altloc B and resid 1 and (phosphate or ribose) I am using the phenix GUI. Is there a better place to enter this type of restraint (rather than NCS) that does not care if a P atom is from a Cd or from a Gd residue type? thanks. Best, John -- John Pascal, PhD ph 215.503.4596 Assistant Professor fx 215.923.2117 Thomas Jefferson University Biochemistry & Molecular Biology 233 South 10th Street, BLSB 804 Philadelphia, Pennsylvania 19107 ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.