Peptide α/310-Helix Dimorphism in the Crystal State
Marco Crisma; Michele Saviano; Alessandro Moretto; Quirinus B. Broxterman; Bernard Kaptein; Claudio Toniolo; Journal of the American Chemical Society 129 (2007) 15471–15473; doi:10.1021/ja076656a

data_4110299
_publ_section_title
;
 Peptide \a/310-Helix Dimorphism in the Crystal State
;
_journal_name_full               'Journal of the American Chemical Society'
_journal_page_first              15471
_journal_page_last               15473
_journal_paper_doi               10.1021/ja076656a
_journal_volume                  129
_journal_year                    2007
_chemical_formula_sum            'C106 H184 F24 N16 O20'
_chemical_formula_weight         2458.69
_chemical_name_systematic
;
 Ac-[L-(\aMe)Val]7-NHiPr 
 1,1,1,3,3,3-hexafluoropropan-2-ol bis-solvate
;
_space_group_IT_number           5
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  'C 2y'
_symmetry_space_group_name_H-M   'C 1 2 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                 94.53(8)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   30.677(4)
_cell_length_b                   11.020(2)
_cell_length_c                   38.639(5)
_cell_measurement_reflns_used    48
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      18
_cell_measurement_theta_min      12
_cell_volume                     13022(4)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SIR-2002 (Burla et al., 2003)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 0.991
_diffrn_measured_fraction_theta_max 0.991
_diffrn_measurement_device_type  'Philips PW1100 diffractometer'
_diffrn_measurement_method       '\q-2\q scans'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           CuK\a
_diffrn_radiation_wavelength     1.54178
_diffrn_reflns_av_R_equivalents  0.0277
_diffrn_reflns_av_sigmaI/netI    0.0700
_diffrn_reflns_limit_h_max       32
_diffrn_reflns_limit_h_min       -32
_diffrn_reflns_limit_k_max       11
_diffrn_reflns_limit_k_min       -1
_diffrn_reflns_limit_l_max       41
_diffrn_reflns_limit_l_min       0
_diffrn_reflns_number            9864
_diffrn_reflns_theta_full        55.14
_diffrn_reflns_theta_max         55.14
_diffrn_reflns_theta_min         6.36
_diffrn_standards_decay_%        10
_diffrn_standards_interval_count 100
_diffrn_standards_number         3
_exptl_absorpt_coefficient_mu    0.935
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.254
_exptl_crystal_description       plate
_exptl_crystal_F_000             5232
_exptl_crystal_size_max          0.35
_exptl_crystal_size_mid          0.25
_exptl_crystal_size_min          0.07
_refine_diff_density_max         0.351
_refine_diff_density_min         -0.290
_refine_diff_density_rms         0.066
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   0.7(4)
_refine_ls_extinction_coef       0.00004(3)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     SHELXL
_refine_ls_goodness_of_fit_ref   0.927
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           fullcycle
_refine_ls_number_parameters     1514
_refine_ls_number_reflns         9694
_refine_ls_number_restraints     349
_refine_ls_restrained_S_all      0.918
_refine_ls_R_factor_all          0.1740
_refine_ls_R_factor_gt           0.0878
_refine_ls_shift/su_max          0.125
_refine_ls_shift/su_mean         0.023
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.1684P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.2153
_refine_ls_wR_factor_ref         0.2639
_reflns_number_gt                4548
_reflns_number_total             9694
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ja076656a-file003.cif
_cod_data_source_block           mc103
_cod_original_cell_volume        13021(3)
_cod_database_code               4110299