loop_ _chem_link_bond.link_id _chem_link_bond.value_dist _chem_link_bond.value_dist_esd _chem_link_bond.atom_id_1 _chem_link_bond.atom_1_comp_id _chem_link_bond.atom_id_2 _chem_link_bond.atom_2_comp_id PEPTIDE 1.458 0.019 N 1 CA 1 PEPTIDE 1.525 0.021 CA 1 C 1 PEPTIDE 1.329 0.014 C 1 N 2 PEPTIDE 1.231 0.020 C 1 O 1