_pdbx_struct_chem_comp_feature.ordinal 1 _pdbx_struct_chem_comp_feature.auth_comp_id Q20 _pdbx_struct_chem_comp_feature.auth_seq_id 10 _pdbx_struct_chem_comp_feature.seq_num . _pdbx_struct_chem_comp_feature.pdb_strand_id Q _pdbx_struct_chem_comp_feature.asym_id Q _pdbx_struct_chem_comp_feature.type 'SECONDARY STRUCTURE' _pdbx_struct_chem_comp_feature.details 'Helix of length 4 beginning at atom position C2A.'