Roles of Individual Disulfide Bridges in the Conformation and Activity of μ-Conotoxin GIIIA, a Peptide Blocker of Muscle Sodium Channels
- 138 Downloads
Seven analogs of μ-conotoxin GIIIA (μ-GIIIA), a specific blocker of muscle sodium channels, were synthesized by replacing stepwise the three cystine residues with Ala. The circular dichroism spectra of the analogs suggested that the deletion of disulfide bonds gradually randamized a conformation. The inhibitory effects on the twitch contractions of the rat diaphragm showed that the deletion of one disulfide bond reduced the potency to less than 1 % of control. Monocyclic analogs and a linear analog were almost inactive. Therefore, all three disulfide bridges are essential for stabilizing the specific conformation of μ-GIIIA to show biological activity.
Keywordsμ-Conotoxin GIIIA Sodium channel Disulfide bond Structure–activity relation
Fast atom bombardment-mass spectrometry
High performance liquid chromatography
Nuclear magnetic resonance
The authors wish to express their appreciation to Dr. Hideyoshi Higashi of Mitsubishi Kagaku Institute of Life Sciences for providing measurements of FAB-MS and also to Prof. Scott Pugh of Fukuoka Women’s University for correction of English usage of this manuscript.
Conflict of interest
All authors declare that they have no conflict of interest.
All institutional and national guidelines for the care and use of laboratory animals were followed. This article does not include any studies using human subjects.
- Becker S, Prusak-Sochaczewski E, Zamponi G, Beck-Sickinger AG, Gordon RD, French RJ (1992) Action of derivatives of μ-conotoxin GIIIA on sodium channels. Single amino acid substitution in the toxin separately affect association and dissociation rates. Biochemistry 31:8229–8238PubMedCrossRefGoogle Scholar
- Jones RM, Bulaj G (2000) Conus peptides—combinatorial chemistry at a cone snail’s pace. Curr Opin Drug Discov Dev 3:141–154Google Scholar
- Olivera BM, Cruz LJ, de Santos V, LeCheminant GW, Griffin D, Zeikus R, McIntosh JM, Galyean R, Varga J, Gray WR, Rivier J (1987) Neuronal calcium channel antagonists: discrimination between calcium channel subtypes using omega-conotoxin from Conus magus venom. Biochemistry 26:2086–2090PubMedCrossRefGoogle Scholar
- Sato K, Ohtake A, Nakamura H, Ishida Y (1999) A specific interaction of arginine residue in μ-conotoxin with muscle-type sodium channel. In: Mori A, Ishida M, Clark JF (ed) Guanidino compounds in biology and medicine: 5, Proceedings of the 5th international symposium. Blackwell Science Japan, Chapter 25, pp 231–236Google Scholar
- Wakamatsu K, Kohda D, Hatanaka H, Lancelin J-MY, Oya M, Nakamura H, Inagaki F, Sato K (1992) Structure-activity relationships of μ-conotoxin GIIIA: structure determination of active and inactive sodium channel blocker peptides by NMR and simulated annealing calculations. Biochemistry 31:12577–12584PubMedCrossRefGoogle Scholar