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The structure of the complex of sodium (Na +) and the antibiotic monensin A Structure of a potassium complex of a crown ether, a synthetic ionophore-ion complex. Biological activities of metal ion-binding compounds can be changed in response to the increment of the metal concentration, and based on the latter compounds can be classified as "metal ionophores", "metal chelators" or "metal ...
In biochemistry, steady state refers to the maintenance of constant internal concentrations of molecules and ions in the cells and organs of living systems. [1] Living organisms remain at a dynamic steady state where their internal composition at both cellular and gross levels are relatively constant, but different from equilibrium concentrations. [1]
An example is the long-awaited crystal structure of a voltage-gated potassium channel, which was reported in May 2003. [ 40 ] [ 41 ] One inevitable ambiguity about these structures relates to the strong evidence that channels change conformation as they operate (they open and close, for example), such that the structure in the crystal could ...
The Goldman–Hodgkin–Katz flux equation (or GHK flux equation or GHK current density equation) describes the ionic flux across a cell membrane as a function of the transmembrane potential and the concentrations of the ion inside and outside of the cell.
and the current through a given ion channel is the product of that channel's conductance and the driving potential for the specific ion = where is the reversal potential of the specific ion channel. Thus, for a cell with sodium and potassium channels, the total current through the membrane is given by:
Facilitated diffusion in cell membrane, showing ion channels and carrier proteins. Facilitated diffusion (also known as facilitated transport or passive-mediated transport) is the process of spontaneous passive transport (as opposed to active transport) of molecules or ions across a biological membrane via specific transmembrane integral proteins. [1]
However some claim that there is no scientific base for those systems, and cite several examples for their failure. [15] Electro-osmosis can also be used for self-pumping pores powered by chemical reactions rather than electric fields. This approach, using H 2 O 2, has been demonstrated [16] and modeled with the Nernst-Planck-Stokes equations. [8]
Chemical structure and expected channel forming mechanism for the first attempt at preparing a synthetic ion channel [7]. While semi-synthetic ion channels, often based on modified peptidic channels like gramicidin, had been prepared since the 1970s, the first attempt to prepare a synthetic ion channel was made in 1982 using a substituted β-cyclodextrin.