SOLUTION STRUCTURE OF OMEGA-CONOTOXIN MVIIA USING 2D NMR-SPECTROSCOPY

The solution structure of omega-conotoxin MVIIA (SNX-111), a peptide t oxin from the fish hunting cone snail Conus magus and a high-affinity blocker of N-type calcium channels, was determined by 2D NMR spectrosc opy. The backbones of the best 44 structures match with an average pai rwise RMSD of 0.59 angstroms. The structures contain a short segment o f triple-stranded beta-sheet involving residues 6-8, 20-21, and 24-25. The structure of this toxin is very similar to that of omega-conotoxi n GVIA with which is has only 40% sequence homology, but very similar calcium channel binding affinity and selectivity.