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_4103961
_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 H74 Br Cl3 N8 O11'
_chemical_formula_sum            'C49 H74 Br Cl3 N8 O11'
_chemical_formula_weight         1137.42
_space_group_IT_number           18
_symmetry_cell_setting           orthorhombic
_symmetry_Int_Tables_number      18
_symmetry_space_group_name_Hall  'P 2 2ab'
_symmetry_space_group_name_H-M   'P 21 21 2'
_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                90.00
_cell_formula_units_Z            4
_cell_length_a                   21.942(2)
_cell_length_b                   25.008(3)
_cell_length_c                   10.2160(11)
_cell_measurement_reflns_used    21354
_cell_measurement_temperature    100(2)
_cell_measurement_theta_max      24.7887
_cell_measurement_theta_min      2.1990
_cell_volume                     5605.8(10)
_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 0.997
_diffrn_measured_fraction_theta_max 0.997
_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  0.0411
_diffrn_reflns_av_sigmaI/netI    0.0284
_diffrn_reflns_limit_h_max       25
_diffrn_reflns_limit_h_min       -26
_diffrn_reflns_limit_k_max       29
_diffrn_reflns_limit_k_min       -29
_diffrn_reflns_limit_l_max       12
_diffrn_reflns_limit_l_min       -12
_diffrn_reflns_number            57826
_diffrn_reflns_theta_full        25.06
_diffrn_reflns_theta_max         25.06
_diffrn_reflns_theta_min         1.63
_diffrn_standards_number         0
_exptl_absorpt_coefficient_mu    0.939
_exptl_absorpt_correction_T_max  0.7408
_exptl_absorpt_correction_T_min  0.6773
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
SADABS  (Bruker-AXS, 2003)
;
_exptl_crystal_colour            colorless
_exptl_crystal_density_diffrn    1.348
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       block
_exptl_crystal_F_000             2392
_exptl_crystal_size_max          0.45
_exptl_crystal_size_mid          0.35
_exptl_crystal_size_min          0.34
_refine_diff_density_max         1.413
_refine_diff_density_min         -1.292
_refine_diff_density_rms         0.124
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   0.019(13)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.016
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     660
_refine_ls_number_reflns         9922
_refine_ls_number_restraints     3
_refine_ls_restrained_S_all      1.016
_refine_ls_R_factor_all          0.0771
_refine_ls_R_factor_gt           0.0705
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.1483P)^2^+11.2353P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.2071
_refine_ls_wR_factor_ref         0.2144
_reflns_number_gt                9023
_reflns_number_total             9922
_reflns_threshold_expression     I>2\s(I)
_cod_data_source_file            ja808168y_si_004.cif
_cod_data_source_block           gellman57
_cod_original_cell_volume        5605.8(11)
_cod_original_sg_symbol_Hall     'P 2 2ab     '
_cod_original_sg_symbol_H-M      'P 21 21 2 '
_cod_database_code               4103961