Diversity of Secondary Structure in Catalytic Peptides with β-Turn-Biased Sequences.
Metrano, Anthony J.; Abascal, Nadia C.; Mercado, Brandon Q.; Paulson, Eric K.; Hurtley, Anna E.; Miller, Scott J.; Journal of the American Chemical Society 139 (2017) 492–516; doi:10.1021/jacs.6b11348

data_4125360
_publ_section_title
;
 Diversity of Secondary Structure in Catalytic Peptides with
 \b-Turn-Biased Sequences.
;
_journal_issue                   1
_journal_name_full               'Journal of the American Chemical Society'
_journal_page_first              492
_journal_page_last               516
_journal_paper_doi               10.1021/jacs.6b11348
_journal_volume                  139
_journal_year                    2017
_chemical_absolute_configuration syn
_chemical_formula_moiety         'C29 H50 N6 O6'
_chemical_formula_sum            'C29 H50 N6 O6'
_chemical_formula_weight         578.75
_space_group_crystal_system      orthorhombic
_space_group_IT_number           19
_space_group_name_Hall           'P 2ac 2ab'
_space_group_name_H-M_alt        'P 21 21 21'
_symmetry_space_group_name_Hall  'P 2ac 2ab'
_symmetry_space_group_name_H-M   'P 21 21 21'
_atom_sites_solution_hydrogens   mixed
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-2014/7
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   9.6852(7)
_cell_length_b                   10.7444(8)
_cell_length_c                   31.296(2)
_cell_measurement_reflns_used    772
_cell_measurement_temperature    93(2)
_cell_measurement_theta_max      68.3
_cell_measurement_theta_min      2.8
_cell_volume                     3256.7(4)
_computing_cell_refinement       'CrystalClear-SM Expert 2.0 r15 (Rigaku, 2011)'
_computing_data_collection       'CrystalClear-SM Expert 2.0 r15 (Rigaku, 2011)'
_computing_data_reduction        'CrystalClear-SM Expert 2.0 r15 (Rigaku, 2011)'
_computing_molecular_graphics
; 
 Refinement of F^2^ against ALL reflections.  The weighted R-factor wR and 
 goodness of fit S are based on F^2^, conventional R-factors R are based 
 on F, with F set to zero for negative F^2^. The threshold expression of 
 F^2^ > 2sigma(F^2^) is used only for calculating R-factors(gt) etc. and is 
 not relevant to the choice of reflections for refinement.  R-factors based 
 on F^2^ are statistically about twice as large as those based on F, and R- 
 factors based on ALL data will be even larger. 

The hydrogen atoms were first found in the difference map, then generated 
geometrically and refined as riding atoms with C-H distances = 0.95 - 0.99 
angstroms and Uiso(H) = 1.2 times Ueq(C) for CH and CH2 groups and Uiso(H) 
= 1.5 times Ueq(C) for CH3 groups. The only exceptions are the hydrogen atoms 
on heteroatoms.  These atoms were semi-freely refined. The N-H distances 
converged to chemically unreasonable values, and distance restraints of 0.96(2) 
were subsequently applied to N5-H5, N2A-H2A, and N3-H3. H2B was refined as a riding
atom on N2B, with Uiso(H) = 1.2 times Ued(N). A number of hydrogen 
bonds were refined and are listed in the appended RES file.  The cyclohexyl 
group was modeled as a disordered chair flip over two positions.  The site 
occupancies were freely refined to a converged value of 0.632(6) and 0.369(6), 
for the major (atoms with "B" suffixes) and minor (atoms with "A" suffixes) 
components. The atomic displacement parameters were restrained to have similar 
directions within the major and minor disordered groups. The C-O distance of
the carbonyl with atoms C3-O1 was expected to be chemically similar between major
and minor components; the refinement was restrained to reflect assertion.
;
_computing_publication_material  'SHELXL-2013/2 (Sheldrick, 2014)'
_computing_structure_refinement  'SHELXL-2014/7 (Sheldrick, 2014)'
_computing_structure_solution    'SHELXT-2014/5 (Sheldrick, 2014)'
_diffrn_ambient_temperature      93(2)
_diffrn_detector_area_resol_mean 22.2
_diffrn_measured_fraction_theta_full 0.998
_diffrn_measured_fraction_theta_max 0.995
_diffrn_measurement_device_type  'Rigaku Saturn 944+ CCD'
_diffrn_measurement_method       \w
_diffrn_radiation_type           CuK\a
_diffrn_radiation_wavelength     1.54178
_diffrn_reflns_av_R_equivalents  0.0692
_diffrn_reflns_av_unetI/netI     0.0210
_diffrn_reflns_Laue_measured_fraction_full 0.998
_diffrn_reflns_Laue_measured_fraction_max 0.995
_diffrn_reflns_limit_h_max       11
_diffrn_reflns_limit_h_min       -11
_diffrn_reflns_limit_k_max       12
_diffrn_reflns_limit_k_min       -12
_diffrn_reflns_limit_l_max       37
_diffrn_reflns_limit_l_min       -37
_diffrn_reflns_number            106624
_diffrn_reflns_point_group_measured_fraction_full 0.994
_diffrn_reflns_point_group_measured_fraction_max 0.991
_diffrn_reflns_theta_full        67.679
_diffrn_reflns_theta_max         67.942
_diffrn_reflns_theta_min         4.351
_exptl_absorpt_coefficient_mu    0.676
_exptl_absorpt_correction_T_max  0.936
_exptl_absorpt_correction_T_min  0.863
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'Jacobson, R. (1998) Private Communication'
_exptl_crystal_colour            Colorless
_exptl_crystal_density_diffrn    1.180
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       Block
_exptl_crystal_F_000             1256
_exptl_crystal_size_max          0.210
_exptl_crystal_size_mid          0.180
_exptl_crystal_size_min          0.100
_refine_diff_density_max         0.359
_refine_diff_density_min         -0.353
_refine_diff_density_rms         0.037
_refine_ls_abs_structure_details
; 
 Flack x determined using 2052 quotients [(I+)-(I-)]/[(I+)+(I-)] 
 (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259). 
;
_refine_ls_abs_structure_Flack   0.18(6)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.047
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     462
_refine_ls_number_reflns         5882
_refine_ls_number_restraints     145
_refine_ls_restrained_S_all      1.069
_refine_ls_R_factor_all          0.0502
_refine_ls_R_factor_gt           0.0419
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.0461P)^2^+1.4000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0990
_refine_ls_wR_factor_ref         0.1044
_reflns_Friedel_coverage         0.752
_reflns_Friedel_fraction_full    0.989
_reflns_Friedel_fraction_max     0.984
_reflns_number_gt                5207
_reflns_number_total             5882
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            ja6b11348_si_009.cif
_cod_data_source_block           007-15102
_cod_depositor_comments
'Adding full bibliography for 4125336--4125366.cif.'
_cod_original_cell_volume        3256.8(4)
_cod_database_code               4125360
_shelx_shelxl_version_number     2014/7
_shelx_estimated_absorpt_t_min   0.871
_shelx_estimated_absorpt_t_max   0.936
_shelx_res_checksum              20011
_shelx_hkl_checksum              50555