loop_ _nef_covalent_links.chain_code_1 _nef_covalent_links.sequence_code_1 _nef_covalent_links.residue_name_1 _nef_covalent_links.atom_name_1 _nef_covalent_links.chain_code_2 _nef_covalent_links.sequence_code_2 _nef_covalent_links.residue_name_2 _nef_covalent_links.atom_name_2 B 3 CYS SG B 6 CYS SG B 5 THR OG1 B 9 GLN C