Observation of noncovalent complexes between margatoxin and the Kv1.3 peptide ligands: A model investigation using ion-spray mass spectrometry.

Margatoxin (MgTX), a 39 amino acid peptide present in the venom of the new world scorpion Centruroides margaritatus, is a potent inhibitor of the voltage-gated potassium channel (Kv1.3) in human peripheral T lymphocytes. Peptide analogs corresponding to the amino acid segments that are located at the rat Kv1.3 putative binding site for the ion channel blockers were synthesized. Gas phase noncovalent complexes of the synthetic analogs of the rat Kv1.3 peptide ligands with MgTX were detected using ion-spray mass spectrometry.