1GEA | pdb_00001gea

RECEPTOR-BOUND CONFORMATION OF PACAP21

SOLUTION NMR

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NMR Experiment
Experiment	Type	Sample Contents	Solvent	Ionic Strength	pH	Pressure	Temperature (K)	Spectrometer
1	TRNOESY	1.7mM PACAP21; 40mM PACAP receptor; 80mM phosphate buffer (pH 6.3)	90% H2O/10% D2O	0.41	6.3	ambient	298
2	TRNOESY	1.7mM PACAP21; 40mM PACAP receptor; 80mM phosphate buffer (pH 6.3)	90% H2O/10% D2O

NMR Spectrometer Information
Spectrometer	Manufacturer	Model	Field Strength
1	Bruker	DRX	800

NMR Refinement
Method	Details	Software
Iterative relaxation matrix analysis (IRMA) and simulated annealing (SA)	The structures are calculated by SA protocol of X-PLOR based on a total of 387 TRNOE-derived distance restraints obtained from the IRMA refinement.	X-PLOR

NMR Ensemble Information
Conformer Selection Criteria	structures with the lowest energy
Conformers Calculated Total Number	200
Conformers Submitted Total Number	25
Representative Model	12 (closest to the average)

Additional NMR Experimental Information

Details

Both TRNOE and NOE cross peaks were observed in the spectrum: the former reflects the conformation of PACAP21 in the receptor-bound form, while the latter reflects that of unbound PACAP21. Upon addition of a higher affinity ligand, PACAP27, the TRNOE cross peaks were selectively eliminated due to a competitive inhibition of the specific binding of PACAP21 to the receptor. Accordingly, the subtraction of these two spectra yields TRNOE-related cross peaks exclusively.

Computation: NMR Software
#	Classification	Version	Software Name	Author
1	structure solution	X-PLOR	3.1	Brunger, A.T.
2	iterative matrix relaxation	IRMA	30-Jul-90	Kaptein, R.
3	refinement	X-PLOR	3.1	Brunger, A.T.