I am using the following code for a tetramer modelling:

from modeller import *
from modeller.automodel import *    # Load the automodel class
class MyModel(automodel):
    def special_restraints(self, aln):
        s1 = selection(self.chains['A']).only_atom_types('CA')
        s2 = selection(self.chains['B']).only_atom_types('CA')
s3 = selection(self.chains['C']).only_atom_types('CA')
s4 = selection(self.chains['D']).only_atom_types('CA')
self.restraints.symmetry.append(symmetry(s1, s2, s3, s4))
    def user_after_single_model(self):

env = environ()
env.io.atom_files_directory = ['.', '../atom_files']

a = MyModel(env,
            alnfile  = 'qseq1-tseq1.ali' ,     # my alignment filename
            knowns   = 'tseq1',              # code of the tetramer template
            sequence = 'qseq1')              # code of the monomer made with modeller

a.starting_model= 1                
a.ending_model  = 1               

but after running it, the console is showing "raise KeyError <"No such chain: %s" % indx>
KeyError: 'No such chain: A'"

Please help me.


Arijit Ghosh

Arijit Ghosh
4th Year Integrated MSc.
School of Biological Sciences
National Institute of Science Education and Research
Bhubaneswar, Orissa-751005, India
Alternate electronic contact: arijitghosh2009@gmail.com
Handheld: +91-986-171-9393