Letters in Peptide Science

, Volume 1, Issue 6, pp 291–297

Assignment of the three disulfide bonds in ShK toxin: A potent potassium channel inhibitor from the sea anemone Stichodactyla helianthus

  • Jan Pohl
  • Frantisek Hubalek
  • Michael E. Byrnes
  • Kurt R. Nielsen
  • Amina Woods
  • Michael W. Pennington
Article

DOI: 10.1007/BF00119770

Cite this article as:
Pohl, J., Hubalek, F., Byrnes, M.E. et al. Lett Pept Sci (1995) 1: 291. doi:10.1007/BF00119770

Summary

ShK toxin, a 35-residue peptide isolated from the Caribbean sea anemone Stichodactyla helianthus, is a potent inhibitor of the Kv 1.3 potassium channel in lymphocytes. The natural toxin contains three disulfide bonds. The disulfide pairings of the synthetic ShK toxin were elucidated as a prerequisite for studies on its structure-function relationships. The toxin was fragmented at pH 6.5 using either thermolysin or a mixture of trypsin and chymotrypsin followed by thermolysin. The fragments were isolated by RP-HPLC and were identified by sequence analysis and MALDI-TOF mass spectrometry. The three disulfides were unambiguously identified in either proteolytic digest: Cys3 to Cys35, Cys12 to Cys28 and Cys17 to Cys32. The Cys3-Cys35 disulfide, linking the amino- and carboxyl-termini, defines the characteristic cyclic structure of the molecule. A similar disulfide pairing motif is found in the snake venom-derived potassium channel blocker dendrotoxin and the mammalian antibiotic peptide defensins.

Key words

NeurotoxinDisulfide bondsPotassium channel toxinProtein sequence

Copyright information

© ESCOM Science Publishers B.V 1995

Authors and Affiliations

  • Jan Pohl
    • 1
  • Frantisek Hubalek
    • 1
  • Michael E. Byrnes
    • 2
  • Kurt R. Nielsen
    • 2
  • Amina Woods
    • 3
  • Michael W. Pennington
    • 2
  1. 1.Microchemical FacilityEmory UniversityAtlantaU.S.A.
  2. 2.Bachem Bioscience Inc.King of PrussiaU.S.A.
  3. 3.Oncology DepartmentJohns Hopkins School of MedicineBaltimoreU.S.A.