Revisit of alpha-chitin crystal structure using high resolution X-ray diffraction data.
Sikorski, Pawel; Hori, Ritsuko; Wada, Masahisa; Biomacromolecules 10 (2009) 1100–1105; doi:10.1021/bm801251e

data_1516345
_publ_section_title
;
 Revisit of alpha-chitin crystal structure using high resolution X-ray
 diffraction data.
;
_journal_issue                   5
_journal_name_full               Biomacromolecules
_journal_page_first              1100
_journal_page_last               1105
_journal_paper_doi               10.1021/bm801251e
_journal_volume                  10
_journal_year                    2009
_chemical_formula_sum            'C32 H52 N4 O20'
_chemical_formula_weight         812.78
_chemical_name_systematic
; 
 ? 
;
_space_group_IT_number           19
_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            1
_cell_length_a                   4.715(19)
_cell_length_b                   18.770(5)
_cell_length_c                   10.333(10)
_cell_measurement_temperature    293(2)
_cell_volume                     914(4)
_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution    'SHELXS-97 (Sheldrick, 1990)'
_diffrn_ambient_temperature      293(2)
_diffrn_measured_fraction_theta_full 0.750
_diffrn_measured_fraction_theta_max 0.750
_diffrn_radiation_monochromator  graphite
_diffrn_radiation_source         'fine-focus sealed tube'
_diffrn_radiation_wavelength     0.72930
_diffrn_reflns_av_R_equivalents  0.0000
_diffrn_reflns_av_sigmaI/netI    0.1338
_diffrn_reflns_limit_h_max       3
_diffrn_reflns_limit_h_min       0
_diffrn_reflns_limit_k_max       10
_diffrn_reflns_limit_k_min       0
_diffrn_reflns_limit_l_max       6
_diffrn_reflns_limit_l_min       0
_diffrn_reflns_number            144
_diffrn_reflns_theta_full        14.03
_diffrn_reflns_theta_max         14.03
_diffrn_reflns_theta_min         2.23
_exptl_absorpt_coefficient_mu    0.123
_exptl_crystal_density_diffrn    1.476
_exptl_crystal_density_method    'not measured'
_exptl_crystal_F_000             432
_refine_diff_density_max         0.395
_refine_diff_density_min         -0.242
_refine_diff_density_rms         0.112
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   0(10)
_refine_ls_extinction_coef       0.000(11)
_refine_ls_extinction_expression Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^
_refine_ls_extinction_method     SHELXL
_refine_ls_goodness_of_fit_ref   2.453
_refine_ls_hydrogen_treatment    mixed
_refine_ls_matrix_type           full
_refine_ls_number_parameters     71
_refine_ls_number_reflns         144
_refine_ls_number_restraints     59
_refine_ls_restrained_S_all      1.850
_refine_ls_R_factor_all          0.2553
_refine_ls_R_factor_gt           0.2505
_refine_ls_shift/su_max          2.467
_refine_ls_shift/su_mean         0.230
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.2000P)^2^+0.0000P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
_refine_ls_wR_factor_gt          0.5324
_refine_ls_wR_factor_ref         0.5374
_reflns_number_gt                121
_reflns_number_total             144
_reflns_threshold_expression     >2sigma(I)
_cod_data_source_file            100K.cif
_cod_data_source_block           n21
_cod_database_code               1516345