Rebecca wrote: > I've got a molecule that has a propeptide but there are no chain > designations in the file to distinguish this part of the molecule from the > rest. So, when selecting a region (I'm trying to select only the first 62 > amino acids that consistitute the propiece) PE selects the first 62 and > also > the next 62 (because the residue numbering system begins again from '1' at > the '63rd' amino acid). Any ideas on how to get around this when no chain > designations are provided? I don't know what a propeptide is but ... you could try: select amino & 1-62 OR you could try selecting by atom numbers instead of by residue numbers: select atomno >= 1 & atomno < 999 # or whatever your atom numbers are Miguel