Dear All,

Even with the Coot secondary structure (for example helix) restraint selected and by this way we keep the secondary structure, I find the protein secondary structure formed in this way was not so typpical, for example, not all CO ( i) and NH (i+4) forms H-bonds, and there are H-bonds formed by CO ( i) and NH (i+3). I checks some RCSB PDBs, and find this kind of untypical H-bonds for the Helix backbone were not rare.

Do we accept this kind of untypical H-bonds containing PDB as normal, or do we think we need further refine the structure based on the map?

Smith