Energetics of ion competition in the DEKA selectivity filter of neuronal sodium channels

• Дата: 2015
• Автори: Boda, D., Leaf, G., Fonseca, J., Eisenberg, B.
• Формат: Стаття
• Мова: English
• Опубліковано: Інститут фізики конденсованих систем НАН України 2015
• Назва видання: Condensed Matter Physics
• Онлайн доступ: http://dspace.nbuv.gov.ua/handle/123456789/153512
• Назва журналу: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Цитувати: Energetics of ion competition in the DEKA selectivity filter of neuronal sodium channels / D. Boda, G. Leaf, J. Fonseca, B. Eisenberg // Condensed Matter Physics. — 2015. — Т. 18, № 1. — С. 13601:1-14. — Бібліогр.: 75 назв. — англ.

The energetics of ionic selectivity in the neuronal sodium channels is studied. A simple model constructed for the selectivity filter of the channel is used. The selectivity filter of this channel type contains aspartate (D), glutamate (E), lysine (K), and alanine (A) residues (the DEKA locus). We use Grand Canonical Monte Carlo simulations to compute equilibrium binding selectivity in the selectivity filter and to obtain various terms of the excess chemical potential from a particle insertion procedure based on Widom's method. We show that K⁺ ions in competition with Na⁺ are efficiently excluded from the selectivity filter due to entropic hard sphere exclusion. The dielectric constant of protein has no effect on this selectivity. Ca²⁺ ions, on the other hand, are excluded from the filter due to a free energetic penalty which is enhanced by the low dielectric constant of protein.