Introducing sequential aza-amino acids units induces repeated β-turns and helical conformations in peptides.
Tonali, Nicolo; Correia, Isabelle; Lesma, Jacopo; Bernadat, Guillaume; Ongeri, Sandrine; Lequin, Olivier; Organic & biomolecular chemistry 18 (2020) 3452–3458; doi:10.1039/c9ob02654a

data_7157353
_publ_section_title
;
 Introducing sequential aza-amino acids units induces repeated \b-turns
 and helical conformations in peptides.
;
_journal_issue                   18
_journal_name_full               'Organic &amp; biomolecular chemistry'
_journal_page_first              3452
_journal_page_last               3458
_journal_paper_doi               10.1039/c9ob02654a
_journal_volume                  18
_journal_year                    2020
_chemical_absolute_configuration syn
_chemical_formula_moiety         'C16 H32 N6 O5'
_chemical_formula_sum            'C16 H32 N6 O5'
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_space_group_name_Hall           'P 2yb'
_space_group_name_H-M_alt        'P 1 21 1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     dual
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-2018/3
_audit_update_record
;
2019-08-27 deposited with the CCDC.	2020-02-17 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 108.211(2)
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   10.4497(3)
_cell_length_b                   14.6303(4)
_cell_length_c                   15.2786(5)
_cell_measurement_reflns_used    6319
_cell_measurement_temperature    200(1)
_cell_measurement_theta_max      67
_cell_measurement_theta_min      3
_cell_volume                     2218.83(12)
_computing_cell_refinement       'Bruker SAINT'
_computing_data_collection       'Bruker APEX2'
_computing_data_reduction        'Bruker SAINT'
_computing_molecular_graphics    'SXGRAPH (Farrugia, 2012)'
_computing_publication_material  'WinGX (Farrugia, 2012)'
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_computing_structure_solution    'SHELXT (Sheldrick, 2015)'
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_diffrn_measured_fraction_theta_full 0.985
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_diffrn_measurement_device_type  'Bruker APEX-II CCD'
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_diffrn_reflns_limit_h_min       -12
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_diffrn_reflns_limit_k_min       -17
_diffrn_reflns_limit_l_max       18
_diffrn_reflns_limit_l_min       -18
_diffrn_reflns_number            15632
_diffrn_reflns_point_group_measured_fraction_full 0.771
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_diffrn_reflns_theta_full        67.679
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_exptl_absorpt_correction_T_min  0.94
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
; 
 SADABS : Krause, L., Herbst-Irmer, R., Sheldrick G.M. & Stalke D.,
 J. Appl. Cryst. 48 (2015) 3-10
;
_exptl_crystal_colour            colourless
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_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       plate
_exptl_crystal_F_000             840
_exptl_crystal_recrystallization_method
'Re-crystallisation from solvent: Methanol / diethyl ether'
_exptl_crystal_size_max          0.20
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_refine_ls_abs_structure_details
;
 Flack x determined using 1853 quotients [(I+)-(I-)]/[(I+)+(I-)]
 (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259).
;
_refine_ls_abs_structure_Flack   0.03(11)
_refine_ls_extinction_coef       0.0057(4)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     'SHELXL-2018/3 (Sheldrick 2018)'
_refine_ls_goodness_of_fit_ref   1.037
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     490
_refine_ls_number_reflns         6219
_refine_ls_number_restraints     1
_refine_ls_restrained_S_all      1.037
_refine_ls_R_factor_all          0.0371
_refine_ls_R_factor_gt           0.0347
_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^)+(0.0575P)^2^+0.2256P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0939
_refine_ls_wR_factor_ref         0.0958
_reflns_Friedel_coverage         0.502
_reflns_Friedel_fraction_full    0.539
_reflns_Friedel_fraction_max     0.538
_reflns_number_gt                5852
_reflns_number_total             6219
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            c9ob02654a2.cif
_cod_data_source_block           nt135
_cod_depositor_comments          'Adding full bibliography for 7157353.cif.'
_cod_original_sg_symbol_H-M      'P 21'
_cod_database_code               7157353
_shelx_shelxl_version_number     2018/3
_shelx_res_checksum              37300