Flux, coupling, and selectivity in ionic channels of one conformation.
AUTOR(ES)
Chen, D P
RESUMO
Ions crossing biological membranes are described as a concentration of charge flowing through a selective open channel of one conformation and analyzed by a combination of Poisson and Nernst-Planck equations and boundary conditions, called the PNP theory for short. The ion fluxes in this theory interact much as ion fluxes interact in biological channels and mediated transporters, provided the theoretical channel contains permanent charge and has selectivity created by (electro-chemical) resistance at its ends. Interaction occurs because the flux of different ionic species depends on the same electric field. That electric field is a variable, changing with experimental conditions because the screening (i.e., shielding) of the permanent charge within the channel changes with experimental conditions. For example, the screening of charge and the shape of the electric field depend on the concentration of all ionic species on both sides of the channel. As experimental interventions vary the screening, the electric field varies, and thus the flux of each ionic species varies conjointly, and is, in that sense, coupled. Interdependence and interaction are the rule, independence is the exception, in this channel.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1225775Documentos Relacionados
- Revisiting the ionic selectivity of Na+ channels.
- Control of ion flux and selectivity by negatively charged residues in the outer mouth of rat sodium channels.
- Intramolecular energy transfer and molecular conformation.
- Adenovirus DNA. I. Molecular weight and conformation.
- 5-Nitrouridine-monohydrate: crystal structure and conformation.