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C(alpha)H...O hydrogen bonds were a surprise to me. Kleiger and Eisenberg JMB 2002, 323, 69-76. I have to run in a second, but... My guess is that the "FREE" or "CONN" or "BUMP" instructions might override the anti-bump restraint. -Dan On Thu, 10 Aug 2006, Artem Lyubimov wrote: > *** For details on how to be removed from this list visit the *** > *** CCP4 home page http://www.ccp4.ac.uk *** > > > Hi all, > > I am using SHELX to refine a protein structure where electron density > clearly shows what appears to be a rather strong CH - O hydrogen bond > between two residues (i.e. Met and Asp are within 2.5A of one > another). However, SHELX seems to interpret that as a steric clash > and the two residues are pushed apart (and out of density) in the > refinement. I'm trying different things to convince SHELX that those > atoms indeed belong this close together, but I'd like to ask the pros > for ideas, as well. I would prefer to avoid fixing the coordinates > of the residues, and using BIND to simulate covalent connectivity > between those atoms also seems like a misrepresentation of the > situation. So, is there a way to manually specify an individual > hydrogen bond in SHELX, rather than let the program find it? I can't > find anything about that in the manual. Alternatively, is there a > way to selectively turn off the anti-bumping restraints for a group > of atoms? I seem to remember a brief discussion on the matter in > this forum, and the answer appears to be "no", but I thought I'd ask > anyway. > > Thanks! > Art >
