1QAE

THE ACTIVE SITE OF SERRATIA ENDONUCLEASE CONTAINS A CONSERVED MAGNESIUM-WATER CLUSTER

X-RAY DIFFRACTION

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Crystallization

Crystalization Experiments
ID	Method	pH	Temperature	Details
1	VAPOR DIFFUSION, SITTING DROP	8.2	277	CRYSTALLIZATION METHOD: VAPOR DIFFUSION SITTING DROP CRYSTALLIZATION TEMPERATURE: 277 K CRYSTALLIZATION PH: 4.6 CRYSTALS WERE GROWN FROM PEG 3350, AMMONIUM SULFATE, SODIUM ACETATE, AND STORED IN A STABILIZATION SOLUTION CONTAINING 20% PEG 3000, 400mM GLYCINE, 40mM TRIS, PH8.2 (293 K), 20% PEG 3000, 10% PEG 400. THIS SOLUTION WAS EXCHANGED THREE TIMES TO MINIMIZE CARRY OVER FROM THE STORAGE SOLUTION. AFTER 3 DAYS IN THE MAGNESIUM STABILIZATION SOLUTION, THE CRYSTAL OF DIMENSION 0.4 X 0.4 X 0.3 MM**2 WAS MOUNTED IN A SILICONIZED SPECIAL GLASS CAPILLARY. , VAPOR DIFFUSION, SITTING DROP

Crystal Properties
Matthews coefficient	Solvent content
2.57	52

Crystal Data

Unit Cell
Length ( Å )	Angle ( ˚ )
a = 106.7	α = 90
b = 74.5	β = 90
c = 68.9	γ = 90

Symmetry
Space Group	P 21 21 2

Diffraction

Diffraction Experiment
ID #	Crystal ID	Scattering Type	Data Collection Temperature	Detector	Detector Type	Details	Collection Date	Monochromator	Protocol
1	1	x-ray	288	DIFFRACTOMETER	ENRAF-NONIUS FAST		1998-02-02	M	SINGLE WAVELENGTH

Radiation Source
ID #	Source	Type	Wavelength List	Synchrotron Site	Beamline
1	ROTATING ANODE	RIGAKU RU200

Data Collection

Overall
ID #	Resolution (High)	Resolution (Low)	Percent Possible (Observed)	R Merge 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	2.05	45	84.3	0.025	40.87	3.1		30574			6.6

Highest Resolution Shell
ID #	Resolution (High)	Resolution (Low)	Percent Possible (All)	Percent Possible (Observed)	R Merge I (Observed)	Mean I Over Sigma (Observed)	Redundancy	Number Unique Reflections (All)
	2.05	2.1	20.4		0.045	18.9	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-Work	R-Free	R-Free Selection Details	Mean Isotropic B
X-RAY DIFFRACTION		THROUGHOUT	1.4 ANGSTROM STRUCTURE OF THE SERRATIAL ENDONUCLEASE (CAI, MILLER AND KRAUSE) WITH WATER AND ALTERNATE SIDE CHAIN CONFORMERS REMOVED AND THE SIDE CHAINS FOR THE ACTIVE SITE RESIDUES ARG 57, HIS 89, ASN 199 AND GLU 127 OMITTED	2.05	50	2	29209	1483	83	0.167	0.21	RANDOM	14.8

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
x_dihedral_angle_d	26.6
x_scangle_it	3.53
x_scbond_it	2.32
x_mcangle_it	1.83
x_angle_deg	1.3
x_mcbond_it	1.12
x_improper_angle_d	0.61
x_bond_d	0.005
x_bond_d_na
x_bond_d_prot
x_angle_d
x_angle_d_na
x_angle_d_prot
x_angle_deg_na
x_angle_deg_prot
x_dihedral_angle_d_na
x_dihedral_angle_d_prot
x_improper_angle_d_na
x_improper_angle_d_prot

Non-Hydrogen Atoms Used in Refinement
Non-Hydrogen Atoms	Number
Protein Atoms	3690
Nucleic Acid Atoms
Solvent Atoms	251
Heterogen Atoms	2

Software

Software
Software Name	Purpose
MADNESS	data collection
PROCOR	data scaling
PROCOR	data reduction
XSCALE	data scaling
ARP/wARP	model building
X-PLOR	model building
X-PLOR	refinement
MADNESS	data reduction
X-PLOR	phasing