Preferential closed channel blockade of HERG potassium currents by chemically synthesised BeKm‐1 scorpion toxin

FEBS Letters

Witchel, Harry J¹  Hancox, Jules C¹  Arcangeli, Annarosa²  Crociani, Olivia²  Ridley, John M¹  Dempsey, Christopher E³  Milnes, James T¹ 

[1] Department of Physiology and Cardiovascular Research Laboratories, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK;Department of Experimental Pathology and Oncology, University of Firenze, Viale G.B. Morgagni 50, 50134 Florence, Italy;Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK

关键词: BeKm-1;    Ergtoxin;    Human ether-a-go-go-related gene;    I Kr;    Rapid delayed rectifier;    Scorpion toxin;    Buthus eupeus;    Centruroides noxius;    ANOVA;    analysis of variance;    CI;    95% confidence intervals;    DQF-COSY;    double quantum filtered correlation spectroscopy;    Fmoc;    fluorenylmethoxycarbonyl;    h;    Hill coefficient;    HEK;    human embryonic kidney;    HERG;    human ether-a-go-go-related gene;    HPLC;    high performance liquid chromatography;    IC50;    half-maximal inhibitory drug concentration;    I HERG;    current mediated by the HERG channel;    k;    slope factor describing voltage-dependent activation;    rBeKm-1;    recombinant BeKm-1;    S-to-S;    start-to-start interval;    V 0.5;    half-maximal activation voltage;   

DOI  :  10.1016/S0014-5793(03)00662-8

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The scorpion toxin peptide BeKm-1 was synthesised by fluorenylmethoxycarbonyl solid phase chemistry and folded by air oxidation. The peptide's effects on heterologous human ether-a-go-go-related gene potassium current (I _HERG) in HEK293 cells were assessed using ‘whole-cell’ patch clamp. Blockade of I _HERG by BeKm-1 was concentration-dependent, temperature-dependent, and rapid in onset and reversibility. Blockade also exhibited inverse voltage dependence, inverse dependence on duration of depolarisation, and reverse use- and frequency-dependence. Blockade by BeKm-1 and recombinant ergtoxin, another scorpion toxin known to block HERG, differed in their recovery from HERG current inactivation elicited by strong depolarisation and in their ability to block HERG when the channels were already activated. We conclude that synthetic BeKm-1 toxin blocks HERG preferentially through a closed (resting) state channel blockade mechanism, although some open channel blockade also occurs.

【 授权许可】

Unknown