title: A K+ channel-blocking peptide from venom of Chinese scorpion Buthus martensii Karsch.
abstract: OBJECTIVE
  To purify and characterize a potassium channel blocker (BmP-3) from the venom of Chinese scorpion Buthus martensii Karsch.
  
  
  METHODS
  1. Purification was carried out by gel-filtration, cation-exchange, and reversed-phase chromatographies. N-terminal was directly sequenced by double-coupling manual method. Molecular weight was determined on an electrospray ionization mass spectrometer. Amino acid composition was analyzed after acidic hydrolysis for 20 h in HCl 6 mol.L-1 at 110 degrees C. 2. Toxicity tests were conducted in mice and cockroaches. 3. The inhibitory effects of BmP-3 on K+ channels were tested in acutely dissociated rat hippocampal pyramidal neurons using whole-cell patch-clamp configuration.
  
  
  RESULTS
  1. A pure peptide (BmP-3, 8.1 mg) was obtained, about 0.08% of total proteins of the venom. The N-terminal sequences were VGCEE and the molecular weight was 2938 in ESI-mass spectra. 2. No death occurred at the dosage of 200 micrograms in mice and 8 micrograms in cockroaches. 3. The peptide at 10 mumol.L-1 reduced the peak outward K+ currents by 63% +/- 4% in vitro.
  
  
  CONCLUSIONS
  BmP-3 inhibited K+ channels.
authors.affiliation: State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, China.
authors.forename: G
authors.initials: G
authors.lastname: Wu
authors.forename: D S
authors.initials: DS
authors.lastname: Wei
authors.forename: F H
authors.initials: FH
authors.lastname: He
authors.forename: G Y
authors.initials: GY
authors.lastname: Hu
authors.forename: H M
authors.initials: HM
authors.lastname: Wu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003058:Cockroaches; D006624:Hippocampus / Q000502:physiology; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D009474:Neurons / Q000502:physiology; D026902:Potassium Channel Blockers; D051381:Rats; D017207:Rats, Sprague-Dawley; D012604:Scorpion Venoms / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology / Q000633:toxicity; D016415:Sequence Alignment
chemical_list: C106379:BmP03 toxin; D026902:Potassium Channel Blockers; D012604:Scorpion Venoms