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_7107976
_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         'C39 H58 N4 O7, (C H4 O)'
_chemical_formula_sum            'C40 H62 N4 O8'
_chemical_formula_weight         726.94
_chemical_name_common            'Tetra peptide'
_chemical_name_systematic        'Alpha gamma helix'
_space_group_IT_number           4
_symmetry_cell_setting           monoclinic
_symmetry_Int_Tables_number      4
_symmetry_space_group_name_Hall  'P 2yb'
_symmetry_space_group_name_H-M   'P 1 21 1'
_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                 99.384(5)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   10.132(2)
_cell_length_b                   20.141(4)
_cell_length_c                   21.010(4)
_cell_measurement_temperature    100(2)
_cell_volume                     4230.1(14)
_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 0.999
_diffrn_measured_fraction_theta_max 0.999
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_probe          x-ray
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0699
_diffrn_reflns_av_sigmaI/netI    0.0854
_diffrn_reflns_limit_h_max       13
_diffrn_reflns_limit_h_min       -13
_diffrn_reflns_limit_k_max       16
_diffrn_reflns_limit_k_min       -26
_diffrn_reflns_limit_l_max       27
_diffrn_reflns_limit_l_min       -28
_diffrn_reflns_number            42078
_diffrn_reflns_theta_full        28.28
_diffrn_reflns_theta_max         28.28
_diffrn_reflns_theta_min         1.41
_diffrn_source                   'fine-focus sealed tube'
_diffrn_source_type              'graphite monochromator'
_exptl_absorpt_coefficient_mu    0.079
_exptl_absorpt_correction_T_max  0.975
_exptl_absorpt_correction_T_min  0.967
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   SADABS
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.141
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       'rectangular block'
_exptl_crystal_F_000             1576
_exptl_crystal_recrystallization_method methanol
_exptl_crystal_size_max          0.42
_exptl_crystal_size_mid          0.35
_exptl_crystal_size_min          0.32
_refine_diff_density_max         0.210
_refine_diff_density_min         -0.330
_refine_diff_density_rms         0.044
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   -0.7(10)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   0.952
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     952
_refine_ls_number_reflns         14908
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      0.951
_refine_ls_R_factor_all          0.1495
_refine_ls_R_factor_gt           0.0592
_refine_ls_shift/su_max          2.496
_refine_ls_shift/su_mean         0.051
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0904P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1383
_refine_ls_wR_factor_ref         0.1832
_reflns_number_gt                6991
_reflns_number_total             14908
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            c2cc32911e.txt
_cod_data_source_block           P1
_cod_original_sg_symbol_H-M      'P 21'
_cod_database_code               7107976