6XB1

Room temperature X-ray crystallography reveals catalytic cysteine in the SARS-CoV-2 3CL Mpro is highly reactive: Insights for enzyme mechanism and drug design

X-RAY DIFFRACTION

Starting Model(s)

Initial Refinement Model(s)
Type	Source	Accession Code	Details
experimental model	PDB	6WQF

Crystallization

Crystalization Experiments
ID	Method	pH	Temperature	Details
1	VAPOR DIFFUSION, SITTING DROP	6.5	293	BIS-TRIS pH=6.5, 20% PEG3350

Crystal Properties
Matthews coefficient	Solvent content
1.99	38.3

Crystal Data

Unit Cell
Length ( Å )	Angle ( ˚ )
a = 44.83	α = 90
b = 53.89	β = 100.338
c = 113.588	γ = 90

Symmetry
Space Group	I 1 2 1

Diffraction

Diffraction Experiment
ID #	Crystal ID	Scattering Type	Data Collection Temperature	Detector	Detector Type	Details	Collection Date	Monochromator	Protocol
1	1	x-ray	293	PIXEL	DECTRIS EIGER R 4M		2020-05-04	M	SINGLE WAVELENGTH

Radiation Source
ID #	Source	Type	Wavelength List	Synchrotron Site	Beamline
1	ROTATING ANODE	RIGAKU MICROMAX-007	1.54

Data Collection

Overall
ID #	Resolution (High)	Resolution (Low)	Percent Possible (Observed)	Rpim I (All)	CC (Half)	Net I Over Average Sigma (I)	Redundancy	Number Reflections (All)	Number Reflections (Observed)	Observed Criterion Sigma (F)	Observed Criterion Sigma (I)	B (Isotropic) From Wilson Plot
1	1.8	27.94	94.8	0.031	0.99	10	3.2		23518			24.9

Highest Resolution Shell
ID #	Resolution (High)	Resolution (Low)	Percent Possible (All)	Percent Possible (Observed)	Rpim I (All)	CC (Half)	Mean I Over Sigma (Observed)	Redundancy	Number Unique Reflections (All)
1	1.8	1.84	83.5		0.318	0.796	1.6

Refinement

Statistics
Diffraction ID	Structure Solution Method	Cross Validation method	Starting model	Resolution (High)	Resolution (Low)	Cut-off Sigma (F)	Number Reflections (Observed)	Number Reflections (R-Free)	Percent Reflections (Observed)	R-Factor (Observed)	R-Work	R-Free	Mean Isotropic B
X-RAY DIFFRACTION	MOLECULAR REPLACEMENT	FREE R-VALUE	6WQF	1.8	27.94	1.35	23503	1143	94.73	0.1608	0.1587	0.2019	29.72

Temperature Factor Modeling
Anisotropic B[1][1]	Anisotropic B[1][2]	Anisotropic B[1][3]	Anisotropic B[2][2]	Anisotropic B[2][3]	Anisotropic B[3][3]

RMS Deviations
Key	Refinement Restraint Deviation
f_dihedral_angle_d	19.9714
f_angle_d	1.0898
f_chiral_restr	0.0606
f_bond_d	0.0091
f_plane_restr	0.007

Non-Hydrogen Atoms Used in Refinement
Non-Hydrogen Atoms	Number
Protein Atoms	2369
Nucleic Acid Atoms
Solvent Atoms	129
Heterogen Atoms	9

Software

Software
Software Name	Purpose
PHENIX	refinement
CrysalisPro	data reduction
Aimless	data scaling
MOLREP	phasing

RCSB PDB Core Operations are funded by the U.S. National Science Foundation (DBI-2321666), the US Department of Energy (DE-SC0019749), and the National Cancer Institute, National Institute of Allergy and Infectious Diseases, and National Institute of General Medical Sciences of the National Institutes of Health under grant R01GM157729.