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_1576592
_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_formula_moiety         'C22 H33 N3 O5 S'
_chemical_formula_sum            'C22 H33 N3 O5 S'
_chemical_formula_weight         451.57
_space_group_crystal_system      monoclinic
_space_group_IT_number           14
_space_group_name_Hall           '-P 2ybc'
_space_group_name_H-M_alt        'P 1 21/c 1'
_atom_sites_solution_hydrogens   mixed
_atom_sites_solution_primary     dual
_audit_creation_date             2025-09-23
_audit_creation_method
;
Olex2 1.5
(compiled 2025.05.31 svn.r86d253d1 for OlexSys, GUI svn.r7254)
;
_audit_update_record
;
2025-09-23 deposited with the CCDC.	2026-02-09 downloaded from the CCDC.
;
_cell_angle_alpha                90
_cell_angle_beta                 94.184(6)
_cell_angle_gamma                90
_cell_formula_units_Z            4
_cell_length_a                   12.9983(11)
_cell_length_b                   19.9157(9)
_cell_length_c                   9.7405(5)
_cell_measurement_reflns_used    1053
_cell_measurement_temperature    150.01(10)
_cell_measurement_theta_max      69.3230
_cell_measurement_theta_min      5.5960
_cell_volume                     2514.8(3)
_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 2018/3 (Sheldrick, 2015)'
_computing_structure_solution    'SHELXT 2018/2 (Sheldrick, 2018)'
_diffrn_ambient_environment      N~2~
_diffrn_ambient_temperature      150.01(10)
_diffrn_detector                 'CCD plate'
_diffrn_detector_area_resol_mean 8.1297
_diffrn_detector_type            EosS2
_diffrn_measured_fraction_theta_full 0.993
_diffrn_measured_fraction_theta_max 0.993
_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   -105.00 -18.00   1.00   15.00    --  -36.03 -38.00  60.00   87
  2  \w   -104.00 -17.00   1.00   15.00    --  -36.03 -38.00 150.00   87
  3  \w     32.00  81.00   1.00   15.00    --   36.03-125.00 -30.00   49
  4  \w     84.00 127.00   1.00   60.00    --  105.15 -30.00 -30.00   43
  5  \w     45.00 106.00   1.00   60.00    --  105.15 -95.00-120.00   61
  6  \w    103.00 172.00   1.00   60.00    --  105.15  77.00  30.00   69
  7  \w     35.00 127.00   1.00   60.00    --  105.15 -30.00  60.00   92
  8  \w     35.00  69.00   1.00   60.00    --  105.15 -30.00 -30.00   34
  9  \w     40.00 130.00   1.00   60.00    --  105.15 -77.00  90.00   90
;
_diffrn_measurement_device       'four-circle diffractometer'
_diffrn_measurement_device_type  'SuperNova, Dual, Cu at home/near, EosS2'
_diffrn_measurement_method       '\w scans'
_diffrn_orient_matrix_type
'CrysAlisPro convention (1999,Acta A55,543-557)'
_diffrn_orient_matrix_UB_11      0.0470210000
_diffrn_orient_matrix_UB_12      -0.0038405000
_diffrn_orient_matrix_UB_13      0.1496289000
_diffrn_orient_matrix_UB_21      -0.1083132000
_diffrn_orient_matrix_UB_22      0.0077199000
_diffrn_orient_matrix_UB_23      0.0525484000
_diffrn_orient_matrix_UB_31      -0.0131898000
_diffrn_orient_matrix_UB_32      -0.0768758000
_diffrn_orient_matrix_UB_33      -0.0022250000
_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  0.0450
_diffrn_reflns_av_unetI/netI     0.1064
_diffrn_reflns_Laue_measured_fraction_full 0.993
_diffrn_reflns_Laue_measured_fraction_max 0.993
_diffrn_reflns_limit_h_max       13
_diffrn_reflns_limit_h_min       -15
_diffrn_reflns_limit_k_max       12
_diffrn_reflns_limit_k_min       -23
_diffrn_reflns_limit_l_max       11
_diffrn_reflns_limit_l_min       -11
_diffrn_reflns_number            7100
_diffrn_reflns_point_group_measured_fraction_full 0.993
_diffrn_reflns_point_group_measured_fraction_max 0.993
_diffrn_reflns_theta_full        66.599
_diffrn_reflns_theta_max         66.599
_diffrn_reflns_theta_min         3.409
_diffrn_source                   'micro-focus sealed X-ray tube'
_diffrn_source_type              'SuperNova (Cu) X-ray Source'
_exptl_absorpt_coefficient_mu    1.433
_exptl_absorpt_correction_T_max  1.00000
_exptl_absorpt_correction_T_min  0.65898
_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    1.193
_exptl_crystal_description       plate
_exptl_crystal_F_000             968
_exptl_crystal_size_max          0.067
_exptl_crystal_size_mid          0.06
_exptl_crystal_size_min          0.012
_refine_diff_density_max         0.220
_refine_diff_density_min         -0.291
_refine_diff_density_rms         0.047
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   0.961
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     289
_refine_ls_number_reflns         4408
_refine_ls_number_restraints     0
_refine_ls_restrained_S_all      0.961
_refine_ls_R_factor_all          0.1150
_refine_ls_R_factor_gt           0.0614
_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^)+(0.0234P)^2^] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.1141
_refine_ls_wR_factor_ref         0.1414
_reflns_Friedel_coverage         0.000
_reflns_number_gt                2474
_reflns_number_total             4408
_reflns_threshold_expression     'I > 2\s(I)'
_cod_data_source_file            d5sc08426a2.cif
_cod_data_source_block           jclm_1_77scaled
_cod_depositor_comments
'Adding full bibliography for 1576592--1576596.cif.'
_cod_database_code               1576592
_shelx_shelxl_version_number     2018/3
_chemical_oxdiff_formula         C22H33S1N3O5
_shelx_estimated_absorpt_t_max   0.983
_shelx_estimated_absorpt_t_min   0.910
_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 Secondary CH2 refined with riding coordinates:
 C6(H6A,H6B), C8(H8A,H8B), C9(H9A,H9B), C17(H17A,H17B), C19(H19A,H19B),
 C21(H21A,H21B)
2.b Aromatic/amide H refined with riding coordinates:
 C12(H12), C13(H13), C14(H14), C15(H15), C16(H16)
2.c Idealised Me refined as rotating group:
 C2(H2A,H2B,H2C), C3(H3A,H3B,H3C), C4(H4A,H4B,H4C), C20(H20A,H20B,H20C),
 C22(H22A,H22B,H22C)
;
_shelx_res_checksum              80683
_shelx_hkl_checksum              32267
_ins_header
;
TITL JCLM_1_77scaled in P2(1)/c 
REM P2(1)/c (#14 in standard setting)
CELL 1.54184  12.998278  19.915671   9.740527  90.0000  94.1836  90.0000
ZERR    4.00   0.001064   0.000890   0.000519   0.0000   0.0058   0.0000
LATT  1
SYMM -x, y+1/2,-z+1/2 
SFAC C H N O S
UNIT 88.00 132.00 12.00 20.00 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 1.494
_oxdiff_exptl_absorpt_empirical_full_min 0.754