期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 106, 期 38, 页码 16074-16077出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0903226106
关键词
ion translocation; molecular dynamics simulations; potential of mean force; K+ channels; umbrella sampling
资金
- Engineering and Physical Sciences Research Council
- Leverhulme Trust
- EPSRC [EP/E004539/1] Funding Source: UKRI
- Engineering and Physical Sciences Research Council [EP/E004539/1] Funding Source: researchfish
Potassium channels can conduct passively K+ ions with rates of up to approximate to 10(8) ions per second at physiological conditions, and they are selective to these species by a factor of 10(4) over Na+ ions. Ion conduction has been proposed to involve transitions between 2 main states, with 2 or 3 K+ ions occupying the selectivity filter separated by an intervening water molecule. The largest free energy barrier of such a process was reported to be of the order of 2-3 kcal mol(-1). Here, we present an alternative mechanism for conduction of K+ in potassium channels where site vacancies are involved, and we propose that coexistence of several ion permeation mechanisms is energetically possible. Conduction can be described as a more anarchic phenomenon than previously characterized by the concerted translocations of K+-water-K+.
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