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Biomolecular NMR

X-Filtered NOESY NMR Standard (NEX-XF1)

In an X-filtered experiment, only NOEs between 15N/13C-1H and 14N/12C-1H (e.g. interchain NOEs) protons are observed. NOEs between protons connected to 15N,13C are filtered (intrachain NOEs). When uniformly double-labeled protein sample is mixed with a naturalabundance protein sample, the interface will give rise to the only observable NOESY cross peaks. This powerful strategy enables the spectroscopist to discern intra from inter NOESY cross peaks, thereby providing essential distance constraints for defining the dimer interface (Lee, et al., 1994, 350:87; Palmer, et al., 1991, 93:151; Schleucher, et al., 1994, 4:301).

NEX-XF1 is a 16 kDa protein (A. fulgidus antitoxin vapB21 homodimer) for which a set of resonance assignments (bmr7362), 3D structure (2NWT), and other NMR data are available in the public domain. This is a mixture of unlabeled and uniformly 15N,13C-enriched protein (25% homodimer unlabeled; 50% heterodimer unlabeled/labeled; 25% homodimer labeled) and is perfect to set up X-filtered NOESY experiments.

NEX-XF1 homodimer sample formulation:
NEX-XF1: 13C,15N-labeled and unlabeled sample conditions
1 mM protein, 20 mM NH4OAc pH 5.5, 100 mM NaCl, 5 mM CaCl2, 10% D2O, 0.02 % NaN3
 
X-Filtered NOESY NMR Standard 
 
Catalog No. Label
unlabeled
(15N, 95%)
(13C, 5%; 15N, 95%)
(13C, 95%; 15N, 95%)
(13C, 95%; D, 95%; 15N, 95%)
 (13C, 95%; D, 95%; 15N, 95%; 13CH3-ILV)
(13C, 95%; D, 95%; 15N, 95%; 13CH3-ILVFY)
 
X-Filtered NOESY NMR Standard, His-Tagged
 
Catalog No. Label
unlabeled
(15N, 95%)
(13C, 5%; 15N, 95%)
(13C, 95%; 15N, 95%)
NEX-XF1-HIS-CDN
(13C, 95%; D, 95%; 15N, 95%)
(13C, 95%; D, 95%; 15N, 95%; 13CH3-ILV)
(13C, 95%; D, 95%; 15N, 95%; 13CH3-ILVFY)

 

Protein Sequence

PKIIEAVYENGVFKPLQKVDLKEGERVKIKLELKVEPIDLGEPVSVEEIKKIRDGTWMSSLEHHHHHH