¹H-NMR signal assignments and secondary structure analysis of martentoxin

Abstract

Martentoxin is a peptide of 37 amino acid residues purified from the venom of the Chinese scorpion Buthus martensi Karch, which has been demonstrated to be an inhibitor of voltage-dependent sodium channel and voltage-dependent delayed rectifier potassium channel. To elucidate the molecular mechanism of this interaction, the structure of martentoxin was studied by 2D-NMR. The secondary structure of martentoxin consists of a triple-stranded β-sheet connected to a α-helical structure. This helix encompasses 10 residues from Ser11 to Lys20. The three strands of β-sheet probably comprise residues Gly2-Asp5, Q27-N30 and Glu33-Cys36, Cys30-Asn33 with a type I′β turn centered on Asn31-Asn32. The results indicate that martentoxin possesses the conserved β α β β structure of all the potassium channel toxins.

Keywords:

• Scorpion venom
• Martentoxin
• 2D-NMR
• Sequential assignment
• Secondary structure analysis

Acknowledgements

The authors are thankful to Dr. Guang-Zhong Tu of Beijing Institute of Microchemistry and Dr. Huai-Reng Huang of the Institute of Biophysics, Chinese Academy of Sciences for technical assistance.