Biomedical Engineering Reference
In-Depth Information
Figure 5.16
(a) Unpolarised membrane protein and (b and c) polarised
proteins from the left and right ends, respectively, of the cell in Fig. 5.15b.
process within proteins is fairly rapid in time compared with the
protein diffusion within the plasma membrane.
Now, a second, slower phase starts. This is in accord with
accepted notions of electrophoresis. Since there is now induced
charge separation within proteins, they will start to diffuse. Exactly
how this diffusion takes place is not yet clear, but the proteins
appear to have a charge running down their length. Perhaps on
the extracellular surface there exists a monopole charge on the
protruding parts of the proteins. In the presence of an induced
extracellular tangential component of the E field these monopoles
will diffuse. Inside the membrane, there exists a dipolar charge
separation, that is, a dipole, and the induced tangential membrane
Efieldwillalsocausetheproteinstodiffuse.Withintheintracellular
region, the induced fields will probably cause insignificant diffusion
compared with the other twocomponents of diffusion.
