Subangstrom crystallography reveals that short ionic hydrogen bonds, and not a His-Asp low-barrier hydrogen bond, stabilize the transition state in serine protease catalysis.
Fuhrmann, Cynthia N; Daugherty, Matthew D; Agard, David A; Journal of the American Chemical Society 128 (2006) 9086–9102; doi:10.1021/ja057721o

data_4101247
_publ_section_title
;
 Subangstrom crystallography reveals that short ionic hydrogen bonds,
 and not a His-Asp low-barrier hydrogen bond, stabilize the transition
 state in serine protease catalysis.
;
_journal_issue                   28
_journal_name_full               'Journal of the American Chemical Society'
_journal_page_first              9086
_journal_page_last               9102
_journal_paper_doi               10.1021/ja057721o
_journal_volume                  128
_journal_year                    2006
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_chemical_name_systematic
; 
 ? 
;
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_symmetry_space_group_name_Hall  'P 32 2"'
_symmetry_space_group_name_H-M   'P 32 2 1'
_atom_sites_solution_hydrogens   geom
_atom_sites_solution_primary     direct
_atom_sites_solution_secondary   difmap
_audit_creation_method           SHELXL-97
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_cell_angle_beta                 90.00
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_cell_measurement_temperature    98(2)
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_computing_structure_refinement  'SHELXL-97 (Sheldrick, 1997)'
_computing_structure_solution
;
;
_diffrn_ambient_temperature      98(2)
_diffrn_measured_fraction_theta_full 0.999
_diffrn_measured_fraction_theta_max 0.999
_diffrn_radiation_source
;
;
_diffrn_radiation_wavelength     0.75000
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_diffrn_reflns_limit_h_max       73
_diffrn_reflns_limit_h_min       0
_diffrn_reflns_limit_k_max       0
_diffrn_reflns_limit_k_min       -36
_diffrn_reflns_limit_l_max       88
_diffrn_reflns_limit_l_min       -88
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_diffrn_reflns_theta_full        24.62
_diffrn_reflns_theta_max         24.62
_diffrn_reflns_theta_min         1.11
_exptl_absorpt_coefficient_mu    0.081
_exptl_crystal_density_diffrn    0.852
_exptl_crystal_density_method    'not measured'
_exptl_crystal_F_000             82452
_refine_diff_density_max         0.478
_refine_diff_density_min         -0.365
_refine_diff_density_rms         0.064
_refine_ls_abs_structure_details 'Flack H D (1983), Acta Cryst. A39, 876-881'
_refine_ls_abs_structure_Flack   0(10)
_refine_ls_extinction_method     none
_refine_ls_goodness_of_fit_ref   1.086
_refine_ls_hydrogen_treatment    mixed
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_refine_ls_number_parameters     19963
_refine_ls_number_reflns         146962
_refine_ls_number_restraints     23420
_refine_ls_restrained_S_all      1.021
_refine_ls_R_factor_all          0.0819
_refine_ls_R_factor_gt           0.0733
_refine_ls_shift/su_max          0.001
_refine_ls_shift/su_mean         0.000
_refine_ls_structure_factor_coef Fsqd
_refine_ls_weighting_details
'calc w=1/[\s^2^(Fo^2^)+(0.1720P)^2^+44.3854P] where P=(Fo^2^+2Fc^2^)/3'
_refine_ls_weighting_scheme      calc
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_cod_original_formula_sum        'C846 H2027 B N262 O581 S9.50'
_cod_database_code               4101247