Effects of Lys2 to Ala2 substitutions on the structure and potency of ω-conotoxins MVIIA and CVID.

Lys2 has previously been implicated as a residue important in binding interactions between omega-conotoxins and the N-type calcium channel. To further assess the importance of this residue, Lys2 to Ala2 derivatives of omega-conotoxins MVIIA and CVID were synthesized and their structures and binding potencies determined. A comparison of the 3D structures of the Ala2 mutants with the parent peptides suggest there are significant structural differences brought about by this substitution.

Neuronally micro-conotoxins from Conus striatus utilize an alpha-helical motif to target mammalian sodium channels.

Mu-conotoxins are small peptide inhibitors of muscle and neuronal tetrodotoxin (TTX)-sensitive voltage-gated sodium channels (VGSCs). Here we report the isolation of mu-conotoxins SIIIA and SIIIB by (125)I-TIIIA-guided fractionation of milked Conus striatus venom. SIIIA and SIIIB potently displaced (125)I-TIIIA from native rat brain Na(v)1.

Isolation and structure-activity of mu-conotoxin TIIIA, a potent inhibitor of tetrodotoxin-sensitive voltage-gated sodium channels.

Mu-conotoxins are three-loop peptides produced by cone snails to inhibit voltage-gated sodium channels during prey capture. Using polymerase chain reaction techniques, we identified a gene sequence from the venom duct of Conus tulipa encoding a new mu-conotoxin-TIIIA (TIIIA). A 125I-TIIIA binding assay was established to isolate native TIIIA from the crude venom of Conus striatus.

Solution structure of mu-conotoxin PIIIA, a preferential inhibitor of persistent tetrodotoxin-sensitive sodium channels.

Mu-conotoxins are peptide inhibitors of voltage-sensitive sodium channels (VSSCs). Synthetic forms of mu-conotoxins PIIIA and PIIIA-(2-22) were found to inhibit tetrodotoxin (TTX)-sensitive VSSC current but had little effect on TTX-resistant VSSC current in sensory ganglion neurons. In rat brain neurons, these peptides preferentially inhibited the persistent over the transient VSSC current.