A K+ channel-blocking peptide from venom of Chinese scorpion Buthus martensii Karsch.
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.
Wu
G
G
State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, China.
Wei
D S
DS
He
F H
FH
Hu
G Y
GY
Wu
H M
HM
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
C106379:BmP03 toxin; D026902:Potassium Channel Blockers; D012604:Scorpion Venoms