Alpha-cobratoxin: proton NMR assignments and solution structure.
The solution structure of alpha-cobratoxin, a neurotoxin purified from the venom of the snake Naja naja siamensis, at pH 3.2 is reported. Sequence-specific assignments of the NMR resonances was attained by a combination of a generalized main-chain-directed strategy and of the sequential method. The NMR data show the presence of a triple-stranded beta-sheet (residues 19-25, 36-41, and 52-57), a short helix, and turns. An extensive number of NOE cross peaks were identified in the NOESY NMR maps. These were applied as distance constraints in a molecular modeling protocol which includes distance geometry and dynamical simulated annealing calculations. A single family of structures is observed which fold in such a way that three major loops emerge from a globular head. The solution and crystal structures of alpha-cobratoxin are very similar. This is in clear contrast to results reported for alpha-bungarotoxin where significant differences exist.
Le Goas
R
R
Institut de Chimie des Substances Naturelles, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France.
LaPlante
S R
SR
Mikou
A
A
Delsuc
M A
MA
Guittet
E
E
Robin
M
M
Charpentier
I
I
Lallemand
J Y
JY
D000595:Amino Acid Sequence; D000818:Animals; D003039:Cobra Neurotoxin Proteins / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011522:Protons; D012996:Solutions; D013329:Structure-Activity Relationship
D003039:Cobra Neurotoxin Proteins; D011522:Protons; D012996:Solutions; C025154:alpha-cobratoxin