Abstract: Derivatives of Maurotoxin (MTX) in which the native disulfide bridge pattern (Cys3-Cys24, Cys9-Cys29, Cys19, Cys31-Cys34) has been disrupted are useful for the treatment of pathologies associated with dysfunctioning and/or activation of Ca2+-activated and/or voltage-gated K+ channel subtypes, such as IKCa1 or Kv1.2. In one group of derivatives, one or two of the amino acid residues of maurotoxin have been replaced by different amino acid residues resulting in the disulfide bridge pattern being changed to Cys3-Cys24, Cys9-Cys29, Cys13-Cys31, Cys19-Cys34. Exemplary substitutions include the Arg residue at position 14 and/or the Lys residue at position 15 replaced by a Gln residue and the Gly residue at position 33 replaced by an Ala residue. Pi1 and HsTx1 derivatives with disrupted native disulfide bridge patterns are similarly useful.

Abstract: OsK1 is a 38-residue peptide with 3 disulphide bridges and is found in the venom of the scorpion Orthochirus scrobiculosus. It is potently active on voltage-gated K+ channels Kv1.1, Kv1.2 and Kv1.3, and moderately active on the type 1 intermediate-conductance Cat2+-activated channel KCa3.1. Derivatives of OsK1, particularly involving truncation or point mutations, have been developed to enhance the activity against and selectivity for the Kv1.3 channel. This renders the derivatives likely candidates for the treatment of autoimmune diseases, including multiple sclerosis. Such use may be alone or in combination therapy with maurotoxin, another scorpion toxin.

Abstract: Maurocalcine, a novel toxin isolated from the venom of the Tunisian chactidae scorpion Scorpio maurus palmatus, has the amino acid sequence GDCLPHLKLCKENKDCCSKKCKRRGTNIEKRCR (SEQ. ID. No. 1). It potently and reversibly modifies channel gating behaviour of type 1 ryanodine receptor (RyR1) by inducing prominent subconductance behavior. Maurocalcine and its bioactive structural analogues—preferably those containing the KKCKRR motif corresponding to part of the II-III loop of the alpha1S subunit of the voltage-dependent skeletal muscle calcium channel dihydropyridine receptor—appear to possess a therapeutic potential, notably as candidate immuno-suppressive drugs, and for the treatment of pathologies in humans that may involve a dysfunction of calcium channels.