2FZ5

Solution structure of two-electron reduced Megasphaera elsdenii flavodoxin

SOLUTION NMR

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NMR Experiment
Experiment	Type	Sample Contents	Solvent	Ionic Strength	pH	Pressure	Temperature (K)	Spectrometer
1	COSY	6-10 mM protein, potassium phosphate/potassium pyrophosphate 75-200 mM, pH 8.3, 90% H2O, 10% D2O	90% H2O/10% D2O		8.3		303
2	double quantum filtered COSY	6-10 mM protein, potassium phosphate/potassium pyrophosphate 75-200 mM, pH 8.3, 90% H2O, 10% D2O	90% H2O/10% D2O		8.3		303
3	NOESY (mixing 200ms)	6-10 mM protein, potassium phosphate/potassium pyrophosphate 75-200 mM, pH 8.3, 90% H2O, 10% D2O	90% H2O/10% D2O		8.3		303
4	NOESY (mixing 50, 100, 150 ms)		8.3		303
5	Double Quantum spectra	6-10 mM protein, potassium phosphate/potassium pyrophosphate 75-200 mM, pH 8.3, 90% H2O, 10% D2O	90% H2O/10% D2O		8.3		303
6	Homonuclear Hartmann Hahn transfer spectra	6-10 mM protein, potassium phosphate/potassium pyrophosphate 75-200 mM, pH 8.3, 90% H2O, 10% D2O	90% H2O/10% D2O		8.3		303

NMR Spectrometer Information
Spectrometer	Manufacturer	Model	Field Strength
1	Bruker	WM	500
2	Bruker	AM	500
3	Bruker	AM	600

NMR Refinement
Method	Details	Software
restrained molecular dynamics	The Xray structure of the semiquinone state of Clostridium MP flavodoxin was used as a starting structure for restrained molecular dynamics (RMD) calculations in vacuo (van Mierlo et al. Eur. J. Biochem. 194, 185 - 198 (1990)). 509 distance restraints, 293 medium, 216 long-range were used in refinement. One repulsive restraint, between N5H of FMN and NH of E60 was included. RMD run was of 120 ps. During the first 50 ps the force constant was gradually increased to a high value of 4000 kJmol-1nm-2. From 50 ps on, the force constant was kept constant. The time span of 60-120 ps, at a time resolution of 0.02 ps, was used for calculating the average structure. The time-averaged (not energy minimised) structure has a potential energy -2278 +/- 122 kJmol-1, time-averaged sum of all violations is 2.27 nm, largest occuring violation is 66 pm	DISNMR

NMR Ensemble Information
Conformer Selection Criteria
Conformers Calculated Total Number	3000
Conformers Submitted Total Number	1
Representative Model	1 (averaging the restrained molecular dynamics trajectory in the range 60-120 ps.)

Additional NMR Experimental Information
Details	NOESY spectra had mixing times 50, 100, 150 and 200 ms. Double Quantum spectra had a delay of 32 ms. Homonuclear Hartmann Hahn transfer spectra (using MLEV-17 composite pulse cycling) had mixing times 10-160 ms

Computation: NMR Software
#	Classification	Version	Software Name	Author
1	collection	DISNMR		Bruker
2	structure solution	GROMOS		van Gunsteren and Berendsen
3	refinement	GROMOS		van Gunsteren and Berendsen