ABSTRACT
A novel inhibitor of voltage-gated K(+) channels has been purified to homogeneity from the venom of the black scorpion Orthochirus scrobiculosus. This toxin, named OsK2, has been characterized as a 28-residue peptide, containing six conserved cysteine residues and was shown to be a potent and selective blocker of Kv1.2 channels (K(d) = 97 nM). OsK2 is the second member of the 13th subfamily of short-chain K(+) channel-blocking peptides known thus far and is therefore called alpha-KTx 13.2.
Subject(s)
Potassium Channel Blockers , Potassium Channels, Voltage-Gated , Potassium Channels , Scorpion Venoms/chemistry , Scorpion Venoms/pharmacology , Amino Acid Sequence , Animals , Chromatography , Chromatography, Gel , Chromatography, High Pressure Liquid , Cysteine/chemistry , DNA, Complementary/metabolism , Diptera , Dose-Response Relationship, Drug , Electrophysiology , Grasshoppers , Kinetics , Kv1.2 Potassium Channel , Mass Spectrometry , Molecular Sequence Data , Muscles/drug effects , Neurons/drug effects , Oocytes/metabolism , Peptides/chemistry , Plasmids/metabolism , Scorpion Venoms/isolation & purification , Scorpions , Sequence Analysis, Protein , Sequence Homology, Amino Acid , Time FactorsABSTRACT
alpha-Latrotoxin (alpha-LTX) binding sites to functionally active monoclonal antibodies (MA) A4 and A24 were localized using three approaches: hydrolysis of the toxin followed by the N-terminal sequencing of immunoreactive peptides; the study of antibody interaction with several recombinant alpha-LTX fragments; and Western immunoblotting of synthetic overlapping peptides (6-8 aa) whose structures correspond to that of the immunoreactive alpha-LTX fragment. It was shown that the MA A4 epitope is located within the F234-M294 protein fragment and that of MA A24 interacts with the fragment 347FDKDIT352.
