Hi all. During this and the previous week I have added some improvements to the peptide/protein ribbon object. The ribbons now are nicely coloured by the secondary structure (helix/strand/loop). I found out that previously, the ribbons have had chances to crash and/or lock when created, but now it should be different. But still, the ribbons are drawn for peptide/protein chains detected by the sequence builder object, so there are still these (quite strict) requirements: 1) the chains must be properly capped - in N-terminal with -NH3 or -NH2 groups. - in C-terminal with -COO or -COOH groups. 2) the backbone must consist of proper peptide units: | H-N | R-C-R' | C=O | 3) the minimum chain size is 3 residues. There are no other requirements. For example manually drawn molecules are equivalent to molecules read/imported from any file formats. All that matters are the atoms and bonds that are in the file/system. The most important application for ribbon is displaying imported Protein Databank (PDB) files. Unfortunately, there are problems in many cases where a PDB file is read in (using OpenBabel import) for ribbon display. This is because the PDB file represents experimental data that might be (and often is) incomplete so that the above requirements are not met (for example, some part of a protein crystal might be disordered and/or mobile, so the structure can only be partially solved -> there's a gap in the PDB file -> no ribbon!). For use with ribbons, I added an alternative PDB import function in popup menu location "File/ExtraTools/ImportPDB..." that is designed to read in "complete" PDB files (it ensures completeness for example by joining the gaps in structure (and perhaps modifying the data)). This alternate PDB reader is also slow since it probes the secondary structures; (small file can be ~20 secs but a big one ~15 min!) so let it run for a while; it pro- bably has not locked! So for displaying ribbons I recommend this alternate PDB reader but beware - it might modify the data as I explained above (also a dialog is displayed for users that warns about this). Tommi