Mike White wrote: ... > ValueError: Expected a sequence for model_segment ... > the only change that I made from the script that worked on the single > subunits was to change the "model_segment" parameters from > "('FIRST:'+chain, 'LAST:'+chain)" to "('FIRST:@, LAST:'))".
And that's your problem. Python wants a sequence for model_segment, i.e. two strings separated by a comma, not one string with a comma in it. So you should set model_segment to ('FIRST:@', 'LAST:') instead.
Ben Webb, Modeller Caretaker