Purification, characterization of two peptides from Buthus martensi Karch.
A new peptide named Martentoxin I and an analogue Martentoxin were purified and characterized from the venom of Buthus martensi Karch. Martentoxin I consisted of 36 amino acid residues with molecular mass as 3908.0 Da determined by matrix-assisted laser desorption ionization time-of-flight-MS. The amino acid sequence was determined as GLIDVKCFASSECWTACKKVTGSGQGKCQNNQCRCY by Edman degradation. Martentoxin consisted of 37 amino acid residues with a molecular mass as 4055.3 Da and it showed highly sequence identity to Martentoxin I as FGLIDVKCFASSECWTACKKVTGSGQGKCQNNQCRCY. Estimation from circular dichroism spectra indicated Martentoxin I owned 18.0% alpha-helix, 53.0% beta-sheet structure and 3.9% turn while Martentoxin contained 13.3% alpha-helix, 64.3% beta-sheet structure and 1.1% turn. The toxicity assay showed both peptides had no toxic effects on mice up to the dose of 10 mg/kg. Electrophysiological studies showed that Martentoxin I and Martentoxin at the concentration of 1 microm significantly inhibited voltage-dependent Na+ current (INa) and voltage-dependent delayed rectifier K+ current (IK) but had no effects on transient K+ current (IA). Both interactions with Na+ and K+ channels were irreversible.
Cao
Z Y
ZY
Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China.
Shen
W Q
WQ
Pan
Y P
YP
Xiao
X
X
Liu
X M
XM
Wang
X L
XL
Liang
X T
XT
Yu
D Q
DQ
D000595:Amino Acid Sequence; D000818:Animals; D002942:Circular Dichroism; D004594:Electrophysiology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010455:Peptides / Q000737:chemistry* / Q000302:isolation & purification* / Q000633:toxicity; D011188:Potassium / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012604:Scorpion Venoms / Q000737:chemistry* / Q000302:isolation & purification* / Q000633:toxicity; D012605:Scorpions / Q000737:chemistry*; D012964:Sodium / Q000378:metabolism; D013329:Structure-Activity Relationship
D010455:Peptides; D012604:Scorpion Venoms; C471035:martentoxin, Buthus martensi; D012964:Sodium; D011188:Potassium