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from ost import io
from ost import conop
from promod3 import loop
sequence = "AAAAAAAA"
# the backbone gets initially constructed with backbone dihedrals
# typical for helices
bb_list = loop.BackboneList(sequence)
# let's have a look at the set dihedral angles
for i in range(len(bb_list)):
print("Looking at position %d" % i)
if i > 0:
print("phi: %.4f" % bb_list.GetPhiTorsion(i))
if i < len(bb_list)-1:
print("psi: %.4f" % bb_list.GetPsiTorsion(i))
# we now use a TorsionSampler to set random dihedral angles
torsion_sampler = loop.LoadTorsionSampler()
idx = torsion_sampler.GetHistogramIndex(conop.ALA,
conop.ALA,
conop.ALA)
for i in range(len(bb_list)):
dihedrals = torsion_sampler.Draw(idx)
if i > 0:
bb_list.SetPhiTorsion(i, dihedrals[0])
if i < len(bb_list)-1:
bb_list.SetPsiTorsion(i, dihedrals[1])
# let's save down the randomized fragment
io.SavePDB(bb_list.ToEntity(), "randomized_fragment.pdb")
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