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

Research output: Contribution to journalArticlepeer-review

Abstract

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.

Original languageEnglish (US)
Pages (from-to)291-297
Number of pages7
JournalLetters in Peptide Science
Volume1
Issue number6
DOIs
StatePublished - May 1995

Keywords

  • Disulfide bonds
  • Neurotoxin
  • Potassium channel toxin
  • Protein sequence

ASJC Scopus subject areas

  • Biochemistry

Fingerprint Dive into the research topics of 'Assignment of the three disulfide bonds in ShK toxin: A potent potassium channel inhibitor from the sea anemone Stichodactyla helianthus'. Together they form a unique fingerprint.

Cite this