alpha/gamma^4^-hybrid peptide helices: synthesis, crystal conformations and analogy with the alpha-helix
Anupam Bandyopadhyay; Sandip Jadhav; Hosahudya Gopi; Chem.Commun. 48 (2012) 7170–; doi:10.1039/c2cc32911e

data_7107978
_publ_section_title
;
 alpha/gamma^4^-hybrid peptide helices: synthesis, crystal conformations
 and analogy with the alpha-helix
;
_journal_name_full               Chem.Commun.
_journal_page_first              7170
_journal_paper_doi               10.1039/c2cc32911e
_journal_volume                  48
_journal_year                    2012
_chemical_absolute_configuration syn
_chemical_compound_source        synthesis
_chemical_formula_moiety         '2(C54 H78 N6 O9), O'
_chemical_formula_sum            'C54 H78 N6 O9.5'
_chemical_formula_weight         963.22
_chemical_name_common            HexaD
_chemical_name_systematic        'Alpha-Gamma mixed peptide'
_space_group_IT_number           19
_symmetry_cell_setting           orthorhombic
_symmetry_Int_Tables_number      19
_symmetry_space_group_name_Hall  'P 2ac 2ab'
_symmetry_space_group_name_H-M   'P 21 21 21'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            8
_cell_length_a                   18.113(14)
_cell_length_b                   24.50(2)
_cell_length_c                   27.36(2)
_cell_measurement_temperature    100(2)
_cell_volume                     12142(16)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 2008)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 2008)'
_diffrn_ambient_pressure         101.325
_diffrn_ambient_temperature      100(2)
_diffrn_measured_fraction_theta_full 0.989
_diffrn_measured_fraction_theta_max 0.989
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_probe          x-ray
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.1117
_diffrn_reflns_av_sigmaI/netI    0.2367
_diffrn_reflns_limit_h_max       24
_diffrn_reflns_limit_h_min       -23
_diffrn_reflns_limit_k_max       29
_diffrn_reflns_limit_k_min       -14
_diffrn_reflns_limit_l_max       36
_diffrn_reflns_limit_l_min       -35
_diffrn_reflns_number            54184
_diffrn_reflns_theta_full        28.28
_diffrn_reflns_theta_max         28.28
_diffrn_reflns_theta_min         1.12
_diffrn_source                   'fine-focus sealed tube'
_diffrn_source_type              'Graphite monochromator'
_exptl_absorpt_coefficient_mu    0.072
_exptl_absorpt_correction_T_max  0.991
_exptl_absorpt_correction_T_min  0.976
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   SADABS
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.054
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       'square plate'
_exptl_crystal_F_000             4160
_exptl_crystal_recrystallization_method Acetone
_exptl_crystal_size_max          0.33
_exptl_crystal_size_mid          0.30
_exptl_crystal_size_min          0.12
_refine_diff_density_max         0.292
_refine_diff_density_min         -0.243
_refine_diff_density_rms         0.055
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   -0.7(13)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   0.794
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     1272
_refine_ls_number_reflns         26203
_refine_ls_number_restraints     3
_refine_ls_restrained_S_all      0.798
_refine_ls_R_factor_all          0.2236
_refine_ls_R_factor_gt           0.0826
_refine_ls_shift/su_max          2.090
_refine_ls_shift/su_mean         0.033
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.1000P)^2^+0.7694P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1896
_refine_ls_wR_factor_ref         0.2378
_reflns_number_gt                8437
_reflns_number_total             26203
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            c2cc32911e.txt
_cod_data_source_block           P3
_cod_original_cell_volume        12140(16)
_cod_database_code               7107978