Molecular Dynamics Simulations on Barium Blockades in potassium channels
【摘要】：Potassium channels are a broad family of membrane proteins present in almost every cell, and their rapid and highly selective conduction of potassium ions across membranes is central to many biological and physiological processes [1,2]. Notably, potassium channel such as KcsA is specifically blocked by the Ba~(2+), which shares a similar size while twice the charge as that of the K+. Translocation of Ba~(2+) towards the extracellular side is further prevented when an ion binds to the "external lock-in" site. A mechanism of Ba~(2+) blocking was proposed by an experiment on the KcsA channel in 2011 , and the very recent studies in2014 of the NaK2 K  and MthK  channels, which share an identical selectivity filter structure as that of KcsA, are making the mechanisms proposed above seems to be even more interesting. To thoroughly explore the Ba~(2+) blocking behavior and provide a comprehensive picture of the key elements to Ba~(2+) binding in potassium channels, in terms of CHARMM 36 force field, we carried a systematic comparison study on Ba~(2+) blockade in the above ion channels.