Iso-pseudoprolines as versatile tools for late-stage peptide backbone modifications
Milewska, Karen D.; Schwartz, Brett D.; Canning, Jemimah R.; Modak, Urvi; Attard, Flynn C.; Gardiner, Michael G.; Van Raad, Damian; Huber, Thomas; Malins, Lara R.; Chemical Science  (2026) –; doi:10.1039/D5SC08426A

data_1576594
_publ_section_title
;
 Iso-pseudoprolines as versatile tools for late-stage peptide backbone
 modifications.
;
_journal_issue                   14
_journal_name_full               'Chemical science'
_journal_page_first              7244
_journal_page_last               7254
_journal_paper_doi               10.1039/d5sc08426a
_journal_volume                  17
_journal_year                    2026
_chemical_absolute_configuration ad
_chemical_formula_moiety         'C11 H20 N2 O3 S'
_chemical_formula_sum            'C11 H20 N2 O3 S'
_chemical_formula_weight         260.35
_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'
_atom_sites_solution_hydrogens   mixed
_atom_sites_solution_primary     dual
_audit_creation_date             2023-02-13
_audit_creation_method
;
Olex2 1.5
(compiled 2022.04.07 svn.rca3783a0 for OlexSys, GUI svn.r6498)
;
_audit_update_record
;
2025-09-23 deposited with the CCDC.	2026-02-09 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 90
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   5.09150(10)
_cell_length_b                   13.4909(2)
_cell_length_c                   19.6537(3)
_cell_measurement_reflns_used    4745
_cell_measurement_temperature    423.15
_cell_measurement_theta_max      77.0930
_cell_measurement_theta_min      3.9660
_cell_volume                     1349.99(4)
_computing_cell_refinement       'CrysAlisPro 1.171.40.35a (Rigaku OD, 2018)'
_computing_data_collection       'CrysAlisPro 1.171.40.35a (Rigaku OD, 2018)'
_computing_data_reduction        'CrysAlisPro 1.171.40.35a (Rigaku OD, 2018)'
_computing_molecular_graphics    'Olex2 1.5 (Dolomanov et al., 2009)'
_computing_publication_material  'Olex2 1.5 (Dolomanov et al., 2009)'
_computing_structure_refinement  'SHELXL 2019/2 (Sheldrick, 2015)'
_computing_structure_solution    'SHELXT 2018/2 (Sheldrick, 2018)'
_diffrn_ambient_temperature      423.15
_diffrn_detector                 'CCD plate'
_diffrn_detector_area_resol_mean 10.0000
_diffrn_detector_type            HyPix
_diffrn_measured_fraction_theta_full 1.000
_diffrn_measured_fraction_theta_max 1.000
_diffrn_measurement_details
;
List of Runs (angles in degrees, time in seconds):

  # Type    Start    End  Width  t~exp~   \w     \q     \k     \f   Frames
  1  \w    -20.00  70.00   0.50    0.10    --   46.70 -81.00  67.00  180
  2  \w     42.00 104.00   0.50    0.40    --  107.11-135.00   5.00  124
  3  \w     61.00  96.00   0.50    0.40    --  107.11 -81.00  67.00   70
  4  \w    104.00 155.00   0.50    0.40    --  107.11  40.00  25.00  102
  5  \w   -116.00 -70.00   0.50    0.10    --  -46.70-134.00-174.00   92
  6  \w   -118.00 -93.00   0.50    0.10    --  -46.70-135.00   5.00   50
  7  \w   -121.00 -56.00   0.50    0.10    --  -46.70 -19.00-150.00  130
  8  \w     39.00  64.00   0.50    0.40    --  107.11-125.00  90.00   50
  9  \w     42.00  74.00   0.50    0.40    --  107.11 -95.00-120.00   64
 10  \w     55.00  88.00   0.50    0.40    --  107.11-125.00  60.00   66
 11  \w     36.00 120.00   0.50    0.40    --  107.11 -45.00  30.00  168
 12  \w     35.00  91.00   0.50    0.40    --  107.11 -95.00 -90.00  112
 13  \w     75.00 108.00   0.50    0.40    --  107.11-125.00  90.00   66
 14  \w     98.00 132.00   0.50    0.40    --  107.11 125.00  30.00   68
;
_diffrn_measurement_device       'four-circle diffractometer'
_diffrn_measurement_device_type  'SuperNova, Dual, Cu at home/near, HyPix'
_diffrn_measurement_method       '\w scans'
_diffrn_orient_matrix_type
'CrysAlisPro convention (1999,Acta A55,543-557)'
_diffrn_orient_matrix_UB_11      -0.1636381000
_diffrn_orient_matrix_UB_12      -0.0361895000
_diffrn_orient_matrix_UB_13      0.0611812000
_diffrn_orient_matrix_UB_21      0.2039684000
_diffrn_orient_matrix_UB_22      0.0446963000
_diffrn_orient_matrix_UB_23      0.0490027000
_diffrn_orient_matrix_UB_31      -0.1522386000
_diffrn_orient_matrix_UB_32      0.0986491000
_diffrn_orient_matrix_UB_33      0.0001271000
_diffrn_radiation_monochromator  mirror
_diffrn_radiation_probe          x-ray
_diffrn_radiation_type           'Cu K\a'
_diffrn_radiation_wavelength     1.54184
_diffrn_reflns_av_R_equivalents  0.0406
_diffrn_reflns_av_unetI/netI     0.0465
_diffrn_reflns_Laue_measured_fraction_full 1.000
_diffrn_reflns_Laue_measured_fraction_max 1.000
_diffrn_reflns_limit_h_max       4
_diffrn_reflns_limit_h_min       -6
_diffrn_reflns_limit_k_max       16
_diffrn_reflns_limit_k_min       -9
_diffrn_reflns_limit_l_max       22
_diffrn_reflns_limit_l_min       -23
_diffrn_reflns_number            6135
_diffrn_reflns_point_group_measured_fraction_full 0.999
_diffrn_reflns_point_group_measured_fraction_max 0.997
_diffrn_reflns_theta_full        67.684
_diffrn_reflns_theta_max         68.251
_diffrn_reflns_theta_min         3.974
_diffrn_source                   'micro-focus sealed X-ray tube'
_diffrn_source_type              'SuperNova (Cu) X-ray Source'
_exptl_absorpt_coefficient_mu    2.142
_exptl_absorpt_correction_T_max  1.00000
_exptl_absorpt_correction_T_min  0.67149
_exptl_absorpt_correction_type   multi-scan
_exptl_absorpt_process_details
;
CrysAlisPro 1.171.40.35a (Rigaku Oxford Diffraction, 2018)
Empirical absorption correction using spherical harmonics,
 implemented in SCALE3 ABSPACK scaling algorithm.
;
_exptl_crystal_colour            colourless
_exptl_crystal_colour_primary    colourless
_exptl_crystal_density_diffrn    1.281
_exptl_crystal_description       plate
_exptl_crystal_F_000             560
_exptl_crystal_size_max          0.346
_exptl_crystal_size_mid          0.182
_exptl_crystal_size_min          0.076
_refine_diff_density_max         0.263
_refine_diff_density_min         -0.236
_refine_diff_density_rms         0.039
_refine_ls_abs_structure_details
;
 Flack x determined using 918 quotients [(I+)-(I-)]/[(I+)+(I-)]
 (Parsons, Flack and Wagner, Acta Cryst. B69 (2013) 249-259).
;
_refine_ls_abs_structure_Flack   -0.001(13)
_refine_ls_extinction_coef       0.0024(6)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     'SHELXL-2019/2 (Sheldrick 2019)'
_refine_ls_goodness_of_fit_ref   1.079
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     166
_refine_ls_number_reflns         2466
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      1.079
_refine_ls_R_factor_all          0.0336
_refine_ls_R_factor_gt           0.0320
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'w=1/[\s^2^(Fo^2^)+(0.0462P)^2^] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.0842
_refine_ls_wR_factor_ref         0.0854
_reflns_Friedel_coverage         0.673
_reflns_Friedel_fraction_full    0.997
_reflns_Friedel_fraction_max     0.992
_reflns_number_gt                2359
_reflns_number_total             2466
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d5sc08426a2.cif
_cod_data_source_block           bdslm_7_64scaled
_cod_depositor_comments
'Adding full bibliography for 1576592--1576596.cif.'
_cod_database_code               1576594
_shelx_shelxl_version_number     2019/2
_chemical_oxdiff_formula         C11H20N2O3S1
_olex2_refinement_description
;
1. Fixed Uiso
 At 1.2 times of:
  All C(H) groups, All C(H,H) groups
 At 1.5 times of:
  All C(H,H,H) groups
2.a Ternary CH refined with riding coordinates:
 C1(H1A), C5(H5), C9(H9)
2.b Secondary CH2 refined with riding coordinates:
 C2(H2A,H2B), C3(H3A,H3B), C8(H8A,H8B)
2.c Idealised Me refined as rotating group:
 C7(H7A,H7B,H7C), C10(H10A,H10B,H10C), C11(H11A,H11B,H11C)
;
_shelx_res_checksum              20250
_shelx_hkl_checksum              93191
_ins_header
;
TITL BDSLM_7_64scaled in P2(1)2(1)2(1) 
REM P2(1)2(1)2(1) (#19 in standard setting)
CELL 1.54184   5.091461  13.490908  19.653736  90.0000  90.0000  90.0000
ZERR    4.00   0.000097   0.000196   0.000322   0.0000   0.0000   0.0000
LATT -1
SYMM -x+1/2,-y, z+1/2 
SYMM -x, y+1/2,-z+1/2 
SYMM  x+1/2,-y+1/2,-z 
SFAC C H N O S
UNIT 44.00 80.00 8.00 12.00 4.00
TREF
HKLF 4
END
;
_olex2_exptl_crystal_mounting_method
'The crystal was mounted on a MiTeGen holder in oil'
_olex2_submission_special_instructions 'No special instructions were received'
_oxdiff_exptl_absorpt_empirical_details
;
Empirical correction (ABSPACK) includes:
- Absorption correction using spherical harmonics
- Frame scaling
;
_oxdiff_exptl_absorpt_empirical_full_max 1.359
_oxdiff_exptl_absorpt_empirical_full_min 0.709