Unraveling Solvent-Driven Equilibria between α- and 310-Helices through an Integrated Spin Labeling and Computational Approach
Silvia Carlotto; Paola Cimino; Mirco Zerbetto; Lorenzo Franco; Carlo Corvaja; Marco Crisma; Fernando Formaggio; Claudio Toniolo; Antonino Polimeno; Vincenzo Barone; Journal of the American Chemical Society 129 (2007) 11248–11258; doi:10.1021/ja073516s

data_4109910
_publ_section_title
;
 Unraveling Solvent-Driven Equilibria between \a- and 310-Helices through
 an Integrated Spin Labeling and Computational Approach
;
_journal_name_full               'Journal of the American Chemical Society'
_journal_page_first              11248
_journal_page_last               11258
_journal_paper_doi               10.1021/ja073516s
_journal_volume                  129
_journal_year                    2007
_chemical_formula_sum            'C60 H89 F6 N9 O14'
_chemical_formula_weight         1274.40
_chemical_name_systematic
;
 Fmoc-(Aib)2-TOAC-(Aib)2-TOAC-Aib-OMe
 2,2,2-trifuoroethanol disolvate
;
_space_group_IT_number           14
_symmetry_cell_setting           monoclinic
_symmetry_space_group_name_Hall  '-P 2ybc'
_symmetry_space_group_name_H-M   'P 1 21/c 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                 104.37(7)
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   18.813(3)
_cell_length_b                   17.134(3)
_cell_length_c                   22.355(4)
_cell_measurement_reflns_used    48
_cell_measurement_temperature    293(2)
_cell_measurement_theta_max      19
_cell_measurement_theta_min      12
_cell_volume                     6981(3)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SIR2002 (Burla et al., 2003)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 0.996
_diffrn_measured_fraction_theta_max 0.996
_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  0.0322
_diffrn_reflns_av_sigmaI/netI    0.0317
_diffrn_reflns_limit_h_max       19
_diffrn_reflns_limit_h_min       -19
_diffrn_reflns_limit_k_max       18
_diffrn_reflns_limit_k_min       -1
_diffrn_reflns_limit_l_max       23
_diffrn_reflns_limit_l_min       0
_diffrn_reflns_number            9441
_diffrn_reflns_theta_full        54.23
_diffrn_reflns_theta_max         54.23
_diffrn_reflns_theta_min         3.54
_diffrn_standards_decay_%        negligible
_diffrn_standards_interval_count 100
_diffrn_standards_number         3
_exptl_absorpt_coefficient_mu    0.817
_exptl_absorpt_correction_type   none
_exptl_crystal_colour            orange
_exptl_crystal_density_diffrn    1.213
_exptl_crystal_description       plate
_exptl_crystal_F_000             2712
_exptl_crystal_size_max          0.40
_exptl_crystal_size_mid          0.20
_exptl_crystal_size_min          0.05
_refine_diff_density_max         0.812
_refine_diff_density_min         -0.414
_refine_diff_density_rms         0.098
_refine_ls_extinction_coef       0.00092(14)
_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   1.140
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           fullcycle
_refine_ls_number_parameters     779
_refine_ls_number_reflns         8491
_refine_ls_number_restraints     72
_refine_ls_restrained_S_all      1.137
_refine_ls_R_factor_all          0.1142
_refine_ls_R_factor_gt           0.0890
_refine_ls_shift/su_max          0.063
_refine_ls_shift/su_mean         0.009
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.1802P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.2441
_refine_ls_wR_factor_ref         0.2672
_reflns_number_gt                5803
_reflns_number_total             8491
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            ja073516ssi20070517_051734.cif
_cod_data_source_block           mc113
_cod_original_cell_volume        6981(2)
_cod_database_code               4109910