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 (K_v1.3) in human peripheral T lymphocytes. Peptide analogs corresponding to the amino acid segments that are located at the rat K_v1.3 putative binding site for the ion channel blockers were synthesized. Gas phase noncovalent complexes of the synthetic analogs of the rat K_v1.3 peptide ligands with MgTX were detected using ion-spray mass spectrometry.