Destabilization of the 310-Helix in Peptides Based on Cα-Tetrasubstituted α-Amino Acids by Main-Chain to Side-Chain Hydrogen Bonds
Wojciech M. Wolf; Marcin Stasiak; Miroslav T. Leplawy; Alberto Bianco; Fernando Formaggio; Marco Crisma; Claudio Toniolo; Journal of the American Chemical Society 120 (1998) 11558–11566; doi:10.1021/ja982194c

data_4116889
_publ_section_title
;
 Destabilization of the 310-Helix in Peptides Based on
 C\a-Tetrasubstituted \a-Amino Acids by Main-Chain to Side-Chain Hydrogen
 Bonds
;
_journal_name_full               'Journal of the American Chemical Society'
_journal_page_first              11558
_journal_page_last               11566
_journal_paper_doi               10.1021/ja982194c
_journal_volume                  120
_journal_year                    1998
_chemical_formula_sum            'C44 H65 N5 O18'
_chemical_formula_weight         952.01
_chemical_name_common            Z-[HmS(Ipr)]5-OMe
_space_group_IT_number           2
_symmetry_cell_setting           triclinic
_symmetry_space_group_name_Hall  '-P 1'
_symmetry_space_group_name_H-M   'P -1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
_cell_angle_alpha                98.73(3)
_cell_angle_beta                 102.87(3)
_cell_angle_gamma                98.24(3)
_cell_formula_units_Z            2
_cell_length_a                   11.632(2)
_cell_length_b                   11.945(2)
_cell_length_c                   19.100(2)
_cell_measurement_reflns_used    62
_cell_measurement_temperature    293
_cell_measurement_theta_max      21
_cell_measurement_theta_min      4
_cell_volume                     2513.6(8)
_computing_cell_refinement       'KM4 (Kuma Diffraction, 1994)'
_computing_data_collection       'KM4 (Kuma Diffraction, 1994)'
_computing_data_reduction        'XPREP (Siemens, 1990)'
_computing_molecular_graphics    'XP (Siemens, 1990)'
_computing_publication_material  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      293
_diffrn_measured_fraction_theta_full 0.956
_diffrn_measured_fraction_theta_max 0.956
_diffrn_measurement_device_type  'Kuma Diffraction KM4'
_diffrn_measurement_method       \w--2\q
_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  0.0280
_diffrn_reflns_av_sigmaI/netI    0.0690
_diffrn_reflns_limit_h_max       13
_diffrn_reflns_limit_h_min       -14
_diffrn_reflns_limit_k_max       14
_diffrn_reflns_limit_k_min       -14
_diffrn_reflns_limit_l_max       23
_diffrn_reflns_limit_l_min       -1
_diffrn_reflns_number            10387
_diffrn_reflns_theta_full        69.97
_diffrn_reflns_theta_max         69.97
_diffrn_reflns_theta_min         2.42
_diffrn_standards_decay_%        3
_diffrn_standards_interval_count 100
_diffrn_standards_number         3
_exptl_absorpt_coefficient_mu    0.822
_exptl_absorpt_correction_type   'not applied'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.258
_exptl_crystal_description       prism
_exptl_crystal_F_000             1016
_exptl_crystal_size_max          0.5
_exptl_crystal_size_mid          0.3
_exptl_crystal_size_min          0.15
_refine_diff_density_max         1.151
_refine_diff_density_min         -0.436
_refine_diff_density_rms         0.070
_refine_ls_extinction_coef       0.0025(4)
_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   1.062
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     754
_refine_ls_number_reflns         9129
_refine_ls_number_restraints     186
_refine_ls_restrained_S_all      1.054
_refine_ls_R_factor_all          0.1428
_refine_ls_R_factor_gt           0.0802
_refine_ls_shift/su_max          0.759
_refine_ls_shift/su_mean         0.020
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/['s^2^(Fo^2^)+(0.1335P)^2^+0.2123P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.2151
_refine_ls_wR_factor_ref         0.2485
_reflns_number_gt                5088
_reflns_number_total             9129
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ja982194c_4.cif
_cod_data_source_block           (pentapeptide)
_cod_original_cell_volume        2513.6(10)
_cod_database_code               4116889