Crystallographic Characterization of Helical Secondary Structures in 2:1 and 1:2 α/β-Peptides
Soo Hyuk Choi; Ilia A. Guzei; Lara C. Spencer; Samuel H. Gellman; Journal of the American Chemical Society 131 (2009) 2917–2924; doi:10.1021/ja808168y

data_4103963
_publ_contact_author_address
;
Department of Chemistry
University of Wisconsin-Madison
1101 University Ave
Madison, WI  53706
USA
;
_publ_contact_author_email       iguzei@chem.wisc.edu
_publ_contact_author_fax         608-262-0381
_publ_contact_author_name
;
Guzei, Ilia A. 
;
_publ_contact_author_phone       608-263-4694
_publ_section_title
;
 Crystallographic Characterization of Helical Secondary Structures in 2:1
 and 1:2 \a/\b-Peptides
;
_journal_name_full               'Journal of the American Chemical Society'
_journal_page_first              2917
_journal_page_last               2924
_journal_paper_doi               10.1021/ja808168y
_journal_volume                  131
_journal_year                    2009
_chemical_absolute_configuration ad
_chemical_formula_moiety         'C49 H67 Br N6 O9'
_chemical_formula_sum            'C49 H67 Br N6 O9'
_chemical_formula_weight         964.00
_space_group_IT_number           152
_symmetry_cell_setting           trigonal
_symmetry_Int_Tables_number      152
_symmetry_space_group_name_Hall  'P 31 2"'
_symmetry_space_group_name_H-M   'P 31 2 1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method
;
manual editing of the CIF file 
created by SHELXTL Ver. 6.10
and processed with modiCIfer-09152005. 
;
_cell_angle_alpha                90.00
_cell_angle_beta                 90.00
_cell_angle_gamma                120.00
_cell_formula_units_Z            6
_cell_length_a                   18.5023(10)
_cell_length_b                   18.5023(10)
_cell_length_c                   32.418(4)
_cell_measurement_reflns_used    7592
_cell_measurement_temperature    100(2)
_cell_measurement_theta_max      20.7730
_cell_measurement_theta_min      2.2733
_cell_volume                     9611.0(14)
_computing_cell_refinement       'SAINT Ver. 6.22  (Bruker-AXS, 2003)'
_computing_data_collection       'SMART Ver. 5.622 (Bruker-AXS, 2003)'
_computing_data_reduction        'SAINT Ver. 6.22'
_computing_molecular_graphics    'SHELXTL Ver. 6.10 '
_computing_publication_material  'SHELXTL Ver. 6.10 '
_computing_structure_refinement  'SHELXTL Ver. 6.10 '
_computing_structure_solution    'SHELXTL Ver. 6.10 (Bruker-AXS, 2003)'
_diffrn_ambient_temperature      100(2)
_diffrn_measured_fraction_theta_full 0.999
_diffrn_measured_fraction_theta_max 0.999
_diffrn_measurement_device_type  'Bruker CCD-1000 area detector'
_diffrn_measurement_method       '0.30\% \w scans'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           Mo-K\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.1256
_diffrn_reflns_av_sigmaI/netI    0.0482
_diffrn_reflns_limit_h_max       18
_diffrn_reflns_limit_h_min       -18
_diffrn_reflns_limit_k_max       18
_diffrn_reflns_limit_k_min       -18
_diffrn_reflns_limit_l_max       32
_diffrn_reflns_limit_l_min       -32
_diffrn_reflns_number            68516
_diffrn_reflns_theta_full        20.84
_diffrn_reflns_theta_max         20.84
_diffrn_reflns_theta_min         1.27
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.688
_exptl_absorpt_correction_T_max  0.8100
_exptl_absorpt_correction_T_min  0.7337
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
SADABS  (Bruker-AXS, 2003)
;
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    0.999
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       needle
_exptl_crystal_F_000             3060
_exptl_crystal_size_max          0.48
_exptl_crystal_size_mid          0.45
_exptl_crystal_size_min          0.32
_platon_squeeze_details
;
;
_refine_diff_density_max         1.049
_refine_diff_density_min         -0.557
_refine_diff_density_rms         0.109
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   0.056(16)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.044
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     567
_refine_ls_number_reflns         6741
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.044
_refine_ls_R_factor_all          0.0853
_refine_ls_R_factor_gt           0.0782
_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^)+(0.1618P)^2^+2.1656P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.2047
_refine_ls_wR_factor_ref         0.2105
_reflns_number_gt                5833
_reflns_number_total             6741
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            ja808168y_si_006.cif
_cod_data_source_block           gellman41
_cod_original_cell_volume        9610.9(13)
_cod_original_sg_symbol_Hall     'P 31 2"     '
_cod_original_sg_symbol_H-M      'P 31 2 1 '
_cod_database_code               4103963