Data items in the ENTITY_POLY_SEQ category specify the sequence
of monomers in a polymer. Allowance is made for the possibility
of microheterogeneity in a sample by allowing a given sequence
number to be correlated with more than one monomer ID. The
corresponding ATOM_SITE entries should reflect this
heterogeneity.
loop_
_entity_poly_seq.entity_id
_entity_poly_seq.num
_entity_poly_seq.mon_id
1 1 PRO 1 2 GLN 1 3 ILE 1 4 THR 1 5 LEU
1 6 TRP 1 7 GLN 1 8 ARG 1 9 PRO 1 10 LEU
1 11 VAL 1 12 THR 1 13 ILE 1 14 LYS 1 15 ILE
1 16 GLY 1 17 GLY 1 18 GLN 1 19 LEU 1 20 LYS
1 21 GLU 1 22 ALA 1 23 LEU 1 24 LEU 1 25 ASP
# - - - - data truncated for brevity - - - -