2OQP

Solution structure of human interleukin-21

SOLUTION NMR

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NMR Experiment
Experiment	Type	Sample Contents	Solvent	Ionic Strength	pH	Pressure	Temperature (K)	Spectrometer
1	3D_15N-separated_NOESY	0.8mM IL21 U-15N, 20mM phosphate, 50mM NaCl, 1mM NaN3	90% H2O/10% D2O	50mM NaCl	5.5	ambient	300
2	3D_13C-separated_NOESY	0.8mM IL21 U-15N,13C, 20mM phosphate, 50mM NaCl, 1mM NaN3	100% D2O	50mM NaCl	5.5	ambient	300
3	2D NOESY	0.8mM IL21 U-15N,13C, 20mM phosphate, 50mM NaCl, 1mM NaN3	100% D2O	50mM NaCl	5.5	ambient	300
4	HNHA	0.8mM IL21 U-15N, 20mM phosphate, 50mM NaCl, 1mM NaN3	90% H2O/10% D2O	50mM NaCl	5.5	ambient	300

NMR Spectrometer Information
Spectrometer	Manufacturer	Model	Field Strength
1	Bruker	AV	600
2	Varian	INOVA	800

NMR Refinement
Method	Details	Software
simulated annealing	A total of 1235, 2994 and 449 peaks from 15N-separated, 13C-separated NOESY and 2D NOESY spectra, respectively, were included in structure calculations. Together with chemical shifts for the assigned resonances, the NOEs were analyzed with Cyana using the candid protocol for automatic NOE assignment and structure calculation. Additional sources of structural information were included in the calculations. Thus two disulfide bonds were enforced between Cys43 and Cys94, and between Cys50 and Cys97. This disulfide pattern has been established for the hIL-21 molecule through an analysis which combined protease cleavage, Edman degradation, and MS. Test calculations without disulfide bond constraints supported this pattern. Chemical shift values for HA, CA, CB, N and CO atoms were analyzed to predict phi and psi backbone angles using the computer program Talos. Talos gave good predictions for 78 residues, and 156 angle phi/psi angle constraints were included in the calculations with an uncertainty of 30 degrees. From the HNHA spectrum 72 J(HA-HN) scalar coupling constants were extracted and included in the structure calculations. Hydrogen bond constraints were added for 20 backbone amide protons which exchange slowly in deuterium exchange experiments. Hydrogen bond patterns were identified based on structures calculated without hydrogen bond constraints.	CYANA

NMR Ensemble Information
Conformer Selection Criteria	structures with the lowest energy
Conformers Calculated Total Number	64
Conformers Submitted Total Number	20
Representative Model	1 (lowest energy)

Additional NMR Experimental Information
Details	The structure was determined using triple-resonance NMR spectroscopy.

Computation: NMR Software
#	Classification	Version	Software Name	Author
1	refinement	CYANA	1.0.8	Guntert P.
2	data analysis	TALOS		Cornilescu G., Delaglio F., Bax A.
3	data analysis	Sparky	3.110	Goddard T.D., Kneller D.G.
4	processing	Felix	2004	Accelrys
5	collection	XwinNMR	3.5	Bruker