Physical properties of ion channel

Calculations of the potential energy function of a large number of different globular proteins demonstrate that these proteins all have a very large number of shallow local energy minima (26). This analysis is consistent with the physical properties of ion channel proteins suggested by the fractal properties of the channel data and inconsistent with the few deep minima predicted by the Markov model. 

Thus, the biophysical studies demonstrate that globular proteins have (1) a very large number of conformational states corresponding to many shallow local minima in the potential energy function, (2) very broad continuous distributions of activation energies, and (3) time-dependent activation energy barriers. All these properties are consistent with the physical properties of ion channels derived from the fractal properties observed in the channel data and are inconsistent with the physical properties derived from the Markov model. 

Encapsulation of different entities inside the CNT channel stands alone as an alternative noncovalent functionalization approach. Many studies on the filling of carbon nanotubes with ions or molecules focus on how the presence of these fillers affects the physical properties of the tubes. From a different point of view, confinement of materials inside the cylindrical structure could be regarded as a way to protect such materials from the external environment, with the tubes acting as a nanoreactor or a nanotransporter. It is fascinating to envision specific reactions between molecules occurring inside the aromatic cylindrical framework, tailored by CNT characteristic parameters such as diameter, affinity towards specific molecules, etc. 

The two most essential ion channel properties are ion selectivity and gating. Selectivity is the property of the channels to discriminate among different ions, allowing some to pass through the pore while arresting the flow of others. Gating is the process by which the ion channel is physically opened or closed to permit the transit of ions. 

The Markov description of ion channel kinetics, originally derived from the Hodgkin-Huxley model, implies that the ion channel protein has certain physical properties. 

The discovery of the fractal properties of the single-channel recordings now suggests a different picture of the physical properties of the ion channel protein than the foregoing three properties that were suggested by the Markov model. 

The ability of Ca -channel blockers to influence cytokinin-responses has also been used to adduce second messenger status for Ca. However, the metal ions La and Co are inevitably comparatively non-specific, and also affect both the physical properties of the wall and ethylene biosynthesis respectively. Ca -channel-blocking drugs such as verapamil and nifedipine could only begin to be trusted if their effect on Ca transport in the experimental material had been fully characterized. The discovery that these two Ca channel binders induce callose formation in cells of the liverwort Riella[ 6] indicates that they can facilitate Ca entry in some tissues. Verapamil and nifedipine induced callose in different, discrete regions of the cell which suggests the possibility of diversity within the Ca -channels, an added complication already apparent from the differential sensitivity of Ca -channels in tonoplast and endoplasmic reticulum membrane to inositol 1, 4, 5-trisphosphate [17, 18]. 

There is a significant scatter between the values of the Poiseuille number in micro-channel flows of fluids with different physical properties. The results presented in Table 3.1 for de-ionized water flow, in smooth micro-channels, are very close to the values predicted by the conventional theory. Significant discrepancy between the theory and experiment was observed in the cases when fluid with unknown physical properties was used (tap water, etc.). If the liquid contains even a very small amount of ions, the electrostatic charges on the solid surface will attract the counter-ions in the liquid to establish an electric field. Fluid-surface interaction can be put forward as an explanation of the Poiseuille number increase by the fluid ionic coupling with the surface (Brutin and Tadrist 2003 Ren et al. 2001 Papautsky et al. 1999). 

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