Boda Dezso, Valiskó Mónika, Eisenberg Bob, Nonner Wolfgang, Henderson Douglas, Gillespie Dirk
Department of Molecular Biophysics and Physiology, Rush University Medical Center, Chicago, Illinois 60612, USA.
Phys Rev Lett. 2007 Apr 20;98(16):168102. doi: 10.1103/PhysRevLett.98.168102. Epub 2007 Apr 17.
Calcium-selective ion channels often contain a selectivity filter made of similar amino acids, rich in carboxlylates, although the Ca2+ affinities of these channels range from micromolar to millimolar. To understand the physical mechanism for this range of affinities, we use grand canonical Monte Carlo simulations to study the competition of Na+ and Ca2+ in the selectivity filter of a reduced model of a Ca channel. We show that Ca2+ affinity is increased dramatically when both the volume and dielectric coefficient of the protein are reduced.
钙选择性离子通道通常包含一个由相似氨基酸构成的选择性过滤器，富含羧酸盐，尽管这些通道对Ca2+的亲和力范围从微摩尔到毫摩尔。为了理解这种亲和力范围的物理机制，我们使用巨正则蒙特卡罗模拟来研究Na+和Ca2+在一个简化的钙通道模型的选择性过滤器中的竞争。我们表明，当蛋白质的体积和介电系数都降低时，Ca2+亲和力会显著增加。
