Ester vs. amide on folding: a case study with a 2-residue synthetic peptide.
Vijayadas, Kuruppanthara N.; Nair, Roshna V.; Gawade, Rupesh L.; Kotmale, Amol S.; Prabhakaran, Panchami; Gonnade, Rajesh G.; Puranik, Vedavadi G.; Rajamohanan, Pattuparambil R.; Sanjayan, Gangadhar J.; Organic & biomolecular chemistry 11 (2013) 8348–8356; doi:10.1039/c3ob41967c

data_7153205
_publ_section_title
;
 Ester vs. amide on folding: a case study with a 2-residue synthetic
 peptide.
;
_journal_issue                   48
_journal_name_full               'Organic &amp; biomolecular chemistry'
_journal_page_first              8348
_journal_page_last               8356
_journal_paper_doi               10.1039/c3ob41967c
_journal_volume                  11
_journal_year                    2013
_chemical_absolute_configuration syn
_chemical_formula_moiety         'C21 H22 Br N3 O4'
_chemical_formula_sum            'C21 H22 Br N3 O4'
_chemical_formula_weight         460.33
_space_group_IT_number           19
_symmetry_cell_setting           orthorhombic
_symmetry_space_group_name_Hall  'P 2ac 2ab'
_symmetry_space_group_name_H-M   'P 21 21 21'
_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                 90.00
_cell_angle_gamma                90.00
_cell_formula_units_Z            4
_cell_length_a                   7.1599(7)
_cell_length_b                   11.8460(11)
_cell_length_c                   25.160(2)
_cell_measurement_reflns_used    2359
_cell_measurement_temperature    296(2)
_cell_measurement_theta_max      28.175
_cell_measurement_theta_min      2.958
_cell_volume                     2134.0(3)
_computing_cell_refinement       'SAINT (Bruker, 2003)'
_computing_data_collection       'SMART (Bruker, 2003)'
_computing_data_reduction        'SAINT (Bruker, 2003)'
_computing_molecular_graphics    'ORTEP-3 (Farrugia, 1997)'
_computing_publication_material  'SHELXTL (Bruker, 2003)'
_computing_structure_refinement  'SHELXL97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS97 (Sheldrick, 1997)'
_diffrn_ambient_temperature      296(2)
_diffrn_measured_fraction_theta_full 0.999
_diffrn_measured_fraction_theta_max 0.999
_diffrn_measurement_device_type  'Bruker Smart Apex'
_diffrn_measurement_method       'Phi and Omega Scan'
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_type           MoK\a
_diffrn_radiation_wavelength     0.71073
_diffrn_reflns_av_R_equivalents  0.0724
_diffrn_reflns_av_sigmaI/netI    0.0698
_diffrn_reflns_limit_h_max       8
_diffrn_reflns_limit_h_min       -8
_diffrn_reflns_limit_k_max       13
_diffrn_reflns_limit_k_min       -14
_diffrn_reflns_limit_l_max       29
_diffrn_reflns_limit_l_min       -29
_diffrn_reflns_number            17385
_diffrn_reflns_theta_full        25.00
_diffrn_reflns_theta_max         25.00
_diffrn_reflns_theta_min         1.62
_exptl_absorpt_coefficient_mu    1.958
_exptl_absorpt_correction_T_max  0.9675
_exptl_absorpt_correction_T_min  0.7473
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details   'Bruker's SADABS'
_exptl_crystal_colour            colourless
_exptl_crystal_density_diffrn    1.433
_exptl_crystal_density_method    'not measured'
_exptl_crystal_description       plate
_exptl_crystal_F_000             944
_exptl_crystal_size_max          0.16
_exptl_crystal_size_mid          0.12
_exptl_crystal_size_min          0.02
_refine_diff_density_max         0.535
_refine_diff_density_min         -0.229
_refine_diff_density_rms         0.059
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   0.022(16)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.203
_refine_ls_hydrogen_treatment    constr
_refine_ls_matrix_type           full
_refine_ls_number_parameters     272
_refine_ls_number_reflns         3754
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.203
_refine_ls_R_factor_all          0.1049
_refine_ls_R_factor_gt           0.0749
_refine_ls_shift/su_max          0.000
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.0437P)^2^+0.0329P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1234
_refine_ls_wR_factor_ref         0.1330
_reflns_number_gt                2768
_reflns_number_total             3754
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            c3ob41967c.txt
_cod_data_source_block           3
_cod_original_cell_volume        2134.0(4)
_cod_original_sg_symbol_H-M      P2(1)2(1)2(1)
_cod_database_code               7153205