A K+ channel-blocking peptide from venom of Chinese scorpion Buthus martensii Karsch
Wu, G.; Wei, D.S.; He, F.H.; Hu, G.Y.; Wu, H.M.
Zhongguo Yao Li Xue Bao 19(4): 317-321
1998
ISSN/ISBN: 0253-9756 PMID: 10375775 Document Number: 486851
To purify and characterize a potassium channel blocker (BmP-3) from the venom of Chinese scorpion Buthus martensii Karsch. 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. 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. BmP-3 inhibited K+ channels.