*** For details on how to be removed from this list visit the *** *** CCP4 home page http://www.dl.ac.uk/CCP/CCP4/main.html *** Dear all, Many thanks for all the replies to my question on non-proline cis peptide bond. I will try the toppar parameters provided in the replies, and also want to try REFMAC5. Rong-Jin Guan