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Publication Abstract from PubMed

The nuclear magnetic resonance solution structure of alpha-conotoxin SI has been determined at pH 4.2. The 36 lowest energy structures show that alpha-conotoxin SI exists in a single major solution conformation and is stabilized by six hydrogen bonds. Comparisons are made between the SI solution structure and the solution and crystal structures of alpha-conotoxin GI. Surprisingly, a high degree of similarity between the backbone conformations of the GI crystal and the SI solution structures is seen in the region of lowest sequence homology, namely residues Gly-8 to Ser-12. This similarity is more surprising when considering that in SI a proline replaces the Arg-9 found in GI. The correspondence in conformation in this region provides the definitive evidence that it is the loss of the arginine basic charge at residue 9 which determines the differences in toxicity between GI and SI, rather than any changes in conformation induced by the cyclic proline residue.

Solution structure of alpha-conotoxin SI.,Benie AJ, Whitford D, Hargittai B, Barany G, Janes RW FEBS Lett. 2000 Jul 7;476(3):287-95. PMID:10913630^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.