Ion channel geometry

The present survey has outlined some properties of porous crystals as diffusion media. It has shown some aspects which have been studied insufficiently, such as concentration dependence of D, which may be very important for catalysis at intracrystalline sites. Many more accurate determinations of differential diffusion coefficients are required to give added understanding of the role of concentration, chain length (of paraffins), polarity, exchange ions, channel geometry, and chemical dam-... 

Figure 7. (a) The simulation cell for the ion channel geometry, (b) Illustration of the method... 

In a different context, a micropipette has been applied to monitor the current through a single-ion channel in a biological membrane. The patch-clamp technique invented by Sackmann and Neher [119] led to their Nobel Prize in medicine. The variations in channel current with voltage, concentration, type of ions, and type of channels have been explored. While the functions of specific channels, in particular their ionic selectivity, have been well known, only a handful of channels have the internal geometry and charge distribution determined. The development of a theory to interpret the mass of channel data and to predict channel action is still lacking. 

We have used transferable atom equivalent (TAE) descriptors [116,117] that encode the distributions of electron density based molecular properties, such as kinetic energy densities, local average ionization potentials, Fukui functions, electron density gradients, and second derivatives as well as the density itself. In addition autocorrelation descriptors (RAD) were used and represent the molecular geometry characteristics of the molecules, while they are also canonical and independent of 3D coordinates. The 2D descriptors alone or in combination with the latter 3D descriptors were calculated for 26 data sets collated by us from numerous publications. These data sets encompass various ADME/TOX-related enzymes, transporters, and ion channels as... 

Class 1 neuroreceptor is part of an ion-channel complex (Fig. 4). When a neurotransmitter binds, a conformational change induces the opening of an ion channel. Depending on the geometry and polarity of the "gate" a... 

---