A novel peptide conformation: the γ-bend ribbon.
Drouillat, Bruno; Peggion, Cristina; Biondi, Barbara; Wright, Karen; Couty, François; Crisma, Marco; Formaggio, Fernando; Toniolo, Claudio; Organic & biomolecular chemistry 16 (2018) 7947–7958; doi:10.1039/c8ob02279h

data_7156498
_publ_section_title
;
 A novel peptide conformation: the \g-bend ribbon.
;
_journal_issue                   42
_journal_name_full               'Organic &amp; biomolecular chemistry'
_journal_page_first              7947
_journal_page_last               7958
_journal_paper_doi               10.1039/c8ob02279h
_journal_volume                  16
_journal_year                    2018
_chemical_absolute_configuration syn
_chemical_formula_sum            'C22 H36 N4 O7'
_chemical_formula_weight         468.55
_chemical_name_systematic
;
 Boc-(S)-(\aMe)Aze-(S)-Ala-(S)-(\aMe)Aze-(S)-Ala-OMe
;
_space_group_IT_number           5
_space_group_name_Hall           'I 2y'
_space_group_name_H-M_alt        'I 1 2 1'
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  'I 2y'
_symmetry_space_group_name_H-M   'I 1 2 1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_audit_update_record
;
2018-03-13 deposited with the CCDC.
2018-10-08 downloaded from the CCDC.
;
_cell_angle_alpha                90.00
_cell_angle_beta                 110.085(2)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   20.6903(3)
_cell_length_b                   5.75339(9)
_cell_length_c                   23.2601(3)
_cell_measurement_reflns_used    15490
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      69.2560
_cell_measurement_theta_min      2.0550
_cell_volume                     2600.48(7)
_computing_cell_refinement
;
CrysAlisPro, Agilent Technologies,
Version 1.171.37.31 (release 14-01-2014 CrysAlis171 .NET)
(compiled Jan 14 2014,18:38:05)
;
_computing_data_collection
;
CrysAlisPro, Agilent Technologies,
Version 1.171.37.31 (release 14-01-2014 CrysAlis171 .NET)
(compiled Jan 14 2014,18:38:05)
;
_computing_data_reduction
;
CrysAlisPro, Agilent Technologies,
Version 1.171.37.31 (release 14-01-2014 CrysAlis171 .NET)
(compiled Jan 14 2014,18:38:05)
;
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 2008)'
_computing_structure_solution    'SIR2002 (Burla et al., 2003)'
_diffrn_ambient_temperature      293(2)
_diffrn_detector                 'CCD plate'
_diffrn_detector_area_resol_mean 16.1274
_diffrn_detector_type            Eos
_diffrn_measured_fraction_theta_full 0.996
_diffrn_measured_fraction_theta_max 0.996
_diffrn_measurement_device       'four-circle diffractometer'
_diffrn_measurement_device_type  'Xcalibur, Eos, Gemini'
_diffrn_measurement_method       '\w scans'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'Enhance (Cu) X-ray Source'
_diffrn_radiation_type           CuK\a
_diffrn_radiation_wavelength     1.54178
_diffrn_reflns_av_R_equivalents  0.0296
_diffrn_reflns_av_sigmaI/netI    0.0128
_diffrn_reflns_limit_h_max       24
_diffrn_reflns_limit_h_min       -25
_diffrn_reflns_limit_k_max       6
_diffrn_reflns_limit_k_min       -5
_diffrn_reflns_limit_l_max       28
_diffrn_reflns_limit_l_min       -28
_diffrn_reflns_number            33463
_diffrn_reflns_theta_full        69.42
_diffrn_reflns_theta_max         69.41
_diffrn_reflns_theta_min         2.47
_exptl_absorpt_coefficient_mu    0.742
_exptl_absorpt_correction_T_max  1.00000
_exptl_absorpt_correction_T_min  0.45739
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
CrysAlisPro, Agilent Technologies,
Version 1.171.37.31 (release 14-01-2014 CrysAlis171 .NET)
(compiled Jan 14 2014,18:38:05)
Empirical absorption correction using spherical harmonics,
 implemented in SCALE3 ABSPACK scaling algorithm.
;
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.197
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       needle
_exptl_crystal_F_000             1008
_exptl_crystal_recrystallization_method
'Re-crystallisation from solvent: ethyl acetate / di-isopropyl ether'
_exptl_crystal_size_max          0.50
_exptl_crystal_size_mid          0.20
_exptl_crystal_size_min          0.10
_refine_diff_density_max         0.222
_refine_diff_density_min         -0.147
_refine_diff_density_rms         0.029
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   0.0(2)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.057
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     298
_refine_ls_number_reflns         4498
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.057
_refine_ls_R_factor_all          0.0401
_refine_ls_R_factor_gt           0.0387
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0780P)^2^+0.4976P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1166
_refine_ls_wR_factor_ref         0.1187
_reflns_number_gt                4316
_reflns_number_total             4498
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            c8ob02279h2.cif
_cod_data_source_block           mc229fi
_cod_depositor_comments          'Adding full bibliography for 7156498.cif.'
_cod_original_cell_volume        2600.48(6)
_cod_original_sg_symbol_H-M      'C 1 2 1'
_cod_database_code               7156498