Abstract
Many biological ion channels preferentially conduct large ions over small ions. Here we propose a simple mechanism for this large-particle selectivity. Size selectivity is examined using a hard-sphere model of a binary fluid in a two-compartment system that represents a bath and the selective section of a channel (filter). The solvent is assigned a small repulsive excess chemical potential in the filter. Under these conditions, larger solutes are absorbed into the filter in greater numbers than small solutes because of a negative pressure difference between the filter and the bath. To model the selectivity of ion channels, we extend the model to a hard-sphere electrolyte and a filter that contains, in addition to particles exchanged with the bath, structural ions that are confined to the filter and introduce charge selectivity. This system also selects for the larger ions. For this system, the pressure in the filter varies greatly as a function of bath concentration. Because this would result in large forces acting on the channel protein, we also consider a constant-pressure system and allow the volume to vary. In that case, we observe ion concentration-dependent increases in filter volume and ion density that result in conductance properties observed in some channels.
| Original language | English |
|---|---|
| Pages (from-to) | 4763-4769 |
| Number of pages | 7 |
| Journal | Physical Chemistry Chemical Physics |
| Volume | 4 |
| Issue number | 19 |
| DOIs | |
| State | Published - Oct 30 2002 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Atomic and Molecular Physics, and Optics
Cite this
A physical mechanism for large-ion selectivity of ion channels. / Gillespie, Dirk; Nonner, Wolfgang; Henderson, Douglas; Eisenberg, Robert S.
In: Physical Chemistry Chemical Physics, Vol. 4, No. 19, 30.10.2002, p. 4763-4769.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - A physical mechanism for large-ion selectivity of ion channels
AU - Gillespie, Dirk
AU - Nonner, Wolfgang
AU - Henderson, Douglas
AU - Eisenberg, Robert S.
PY - 2002/10/30
Y1 - 2002/10/30
N2 - Many biological ion channels preferentially conduct large ions over small ions. Here we propose a simple mechanism for this large-particle selectivity. Size selectivity is examined using a hard-sphere model of a binary fluid in a two-compartment system that represents a bath and the selective section of a channel (filter). The solvent is assigned a small repulsive excess chemical potential in the filter. Under these conditions, larger solutes are absorbed into the filter in greater numbers than small solutes because of a negative pressure difference between the filter and the bath. To model the selectivity of ion channels, we extend the model to a hard-sphere electrolyte and a filter that contains, in addition to particles exchanged with the bath, structural ions that are confined to the filter and introduce charge selectivity. This system also selects for the larger ions. For this system, the pressure in the filter varies greatly as a function of bath concentration. Because this would result in large forces acting on the channel protein, we also consider a constant-pressure system and allow the volume to vary. In that case, we observe ion concentration-dependent increases in filter volume and ion density that result in conductance properties observed in some channels.
AB - Many biological ion channels preferentially conduct large ions over small ions. Here we propose a simple mechanism for this large-particle selectivity. Size selectivity is examined using a hard-sphere model of a binary fluid in a two-compartment system that represents a bath and the selective section of a channel (filter). The solvent is assigned a small repulsive excess chemical potential in the filter. Under these conditions, larger solutes are absorbed into the filter in greater numbers than small solutes because of a negative pressure difference between the filter and the bath. To model the selectivity of ion channels, we extend the model to a hard-sphere electrolyte and a filter that contains, in addition to particles exchanged with the bath, structural ions that are confined to the filter and introduce charge selectivity. This system also selects for the larger ions. For this system, the pressure in the filter varies greatly as a function of bath concentration. Because this would result in large forces acting on the channel protein, we also consider a constant-pressure system and allow the volume to vary. In that case, we observe ion concentration-dependent increases in filter volume and ion density that result in conductance properties observed in some channels.
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UR - http://www.scopus.com/inward/citedby.url?scp=0036398845&partnerID=8YFLogxK
U2 - 10.1039/b203184a
DO - 10.1039/b203184a
M3 - Article
AN - SCOPUS:0036398845
VL - 4
SP - 4763
EP - 4769
JO - Physical Chemistry Chemical Physics
JF - Physical Chemistry Chemical Physics
SN - 1463-9076
IS - 19
ER -