Purification of charybdotoxine, a specific inhibitor of the high-conductance Ca/sup 2 +/-activated K/sup +/ channel
Charybdotoxim is a high-affinity specific inhibitor of the high-conductance Ca/sup 2 +/-activated K/sup +/ channel found in the plasma membranes of many vertebrate cell types. Using Ca/sup 2 +/-activated K/sup +/ channels reconstituted into planar lipid bilayer membranes as an assay, the authors have purified the toxin from the venom of the scorpion Leiurus quinquestriatus by a two-step procedure involving chromatofocusing on SP-Sephadex, followed by reversed-phase high-performance liquid chromatography. Charybdotoxin is shown to be a highly basic protein with a mass of 10 kDa. Under the standard assay conditions, the purified toxin inhibits the Ca/sup 2 +/-activated K/sup +/ channel with an apparent dissociation constant of 3.5 nM. The protein is unusually stable, with inhibitory potency being insensitive to boiling or exposure to organic solvents. The toxin's activity is sensitive to chymotrypsin treatment and to acylation of lysine groups. The protein may be radioiodinated without loss of activity.
- Research Organization:
- Brandeis Univ., Waltham, MA
- OSTI ID:
- 6934274
- Journal Information:
- J. Biol. Chem.; (United States), Vol. 261:31
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
MEMBRANE TRANSPORT
INHIBITION
TOXINS
AUTORADIOGRAPHY
PURIFICATION
CALCIUM COMPOUNDS
CATIONS
CELL MEMBRANES
ELECTROPHORESIS
IODINE 125
ION EXCHANGE CHROMATOGRAPHY
POTASSIUM COMPOUNDS
SCORPIONS
SODIUM IODIDES
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
ANIMALS
ANTIGENS
ARACHNIDS
ARTHROPODS
BETA DECAY RADIOISOTOPES
CELL CONSTITUENTS
CHARGED PARTICLES
CHROMATOGRAPHY
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
HALIDES
HALOGEN COMPOUNDS
INORGANIC PHOSPHORS
INTERMEDIATE MASS NUCLEI
INVERTEBRATES
IODIDES
IODINE COMPOUNDS
IODINE ISOTOPES
IONS
ISOTOPES
MATERIALS
MEMBRANES
NUCLEI
ODD-EVEN NUCLEI
PHOSPHORS
RADIOISOTOPES
SEPARATION PROCESSES
SODIUM COMPOUNDS
TOXIC MATERIALS
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