The Characterizations
and Blocking Effects
on Ito of Rat Ventricular Myocyte of New Minipeptides from Buthus
martensi Karsch
TONG Qing-Chun1，2, ZHANG Yi1, ZHOU
Zhao-Nian1 and JI Yong-Hua1，2*
(1Shanghai Institute of Physiology, 2Shanghai
Research Center of Life Science, the Chinese Academy of Sciences, Shanghai
200031, China)
Abstract Two minipeptides (BmP02 and
BmP03) with M.W. 2.950 kD and 2.935 kD determined respectively by electrospray
ionization mass spectrum, were purified from the venom of Buthus martensi
Karsch by an opportune procedure on cation-exchange column chromatography and
repeated HPLC. The amino acid sequence of BmP02 had been determined. Using
whole-cell patch clamp, BmP02 was studied on rat ventricular myocyte. The
results showed that BmP02 inhibited the transient outward current (Ito) of rat
ventricular myocytes with partial recovery after washout (n=5) and its
inhibition had concentration dependence and voltage independence. Further study
showed that BmP02 affected both the inactivation and recovery kinetics, but not
activation kinetics of Ito channel.
Key Words Scorpion toxin； potassium channel； biochemical
purification； whole-cell patch clamp
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