loop_ _pdbx_reference_entity_nonpoly.family_prd_id _pdbx_reference_entity_nonpoly.prd_id _pdbx_reference_entity_nonpoly.ref_entity_id _pdbx_reference_entity_nonpoly.name _pdbx_reference_entity_nonpoly.three_letter_code FAM_000411 PRD_000004 2 "2-CARBOXYQUINOXALINE" QUI