2INQ

Neutron Crystal Structure of Escherichia coli Dihydrofolate Reductase Bound to the Anti-cancer drug, Methotrexate

NEUTRON DIFFRACTION

Crystallization

Crystalization Experiments
ID	Method	pH	Temperature	Details
1		7.5	277	16% (v/v) Polyethylene Glycol 400, 0.2 M CaCl2, 0.1 M Na-HEPES (pH = 7.5); complex [] = 50 mg/ml, Microbatch under parrafin oil, temperature 277K, pH 7.50

Crystal Properties
Matthews coefficient	Solvent content
2.56	52.03

Crystal Data

Unit Cell
Length ( Å )	Angle ( ˚ )
a = 93.12	α = 90
b = 93.12	β = 90
c = 73.87	γ = 120

Symmetry
Space Group	P 61

Diffraction

Diffraction Experiment
ID #	Crystal ID	Scattering Type	Data Collection Temperature	Detector	Detector Type	Details	Collection Date	Monochromator	Protocol
1	1	neutron	293	AREA DETECTOR	TIME-OF-FLIGHT MULTIWIRE HE3 NEUTRON DETECTOR		2005-02-15	L	LAUE

Radiation Source
ID #	Source	Type	Wavelength List	Synchrotron Site	Beamline
1			0.6-7.0

Data Collection

Overall
ID #	Resolution (High)	Resolution (Low)	Percent Possible (Observed)	R Merge I (Observed)	R Sym I (Observed)	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	2.17	38.6	79.7	0.136	0.07	3.7	2.9		14213		1.5

Highest Resolution Shell
ID #	Resolution (High)	Resolution (Low)	Percent Possible (All)	Percent Possible (Observed)	R-Sym I (Observed)	Mean I Over Sigma (Observed)	Redundancy	Number Unique Reflections (All)
1	2.17	2.29	63.7		0.325	1.7	1.7

Refinement

Statistics
Diffraction ID	Structure Solution Method	Cross Validation method	Starting model	Resolution (High)	Resolution (Low)	Cut-off Sigma (F)	Number Reflections (All)	Number Reflections (R-Free)	Percent Reflections (Observed)	R-Work	R-Free	R-Free Selection Details	Mean Isotropic B
NEUTRON DIFFRACTION	FOURIER SYNTHESIS	THROUGHOUT	3DRC (293 K E. COLI DHFR/MTX X-RAY STRUCTURE, 1.7A RESOLUTION)	2.2	6.5	3	14213	702	79.7		0.233	RANDOM

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
s_zero_chiral_vol	0.059
s_anti_bump_dis_restr	0.057
s_non_zero_chiral_vol	0.052
s_angle_d	0.048
s_bond_d	0.046
s_from_restr_planes	0.016
s_similar_dist
s_rigid_bond_adp_cmpnt
s_similar_adp_cmpnt
s_approx_iso_adps

Non-Hydrogen Atoms Used in Refinement
Non-Hydrogen Atoms	Number
Protein Atoms	2516
Nucleic Acid Atoms
Solvent Atoms	152
Heterogen Atoms	66

Software

Software
Software Name	Purpose
d*TREK	data scaling
SHELXL-97	model building
SHELXL-97	refinement
d*TREK	data reduction
CCP4	data scaling
SHELXL-97	phasing

RCSB PDB Core Operations are funded by the National Science Foundation (DBI-1832184), 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 R01GM133198.