Transport nonmonotonous

Considering the highly processive mechanism of the protein degradation by the proteasome, a question naturally arises what is a mechanism behind such translocation rates Let us discuss one of the possible translocation mechanisms. In [52] we assume that the proteasome has a fluctuationally driven transport mechanism and we show that such a mechanism generally results in a nonmonotonous translocation rate. Since the proteasome has a symmetric structure, three ingredients are required for fluctuationally driven translocation the anisotropy of the proteasome-protein interaction potential, thermal noise in the interaction centers, and the energy input. Under the assumption that the protein potential is asymmetric and periodic, and that the energy input is modeled with a periodic force or colored noise, one can even obtain nonmonotonous translocation rates analytically [52]. Here we... 

Fig. 14.8 The case of nonmonotonous transport rate function 1 1. v, shown by a solid line in (a,e,h). From top to bottom different location of the cleavage centre D = 3, 15, 32 (shown the vertical line) with respect to two points where the condition of maximum holds (shown vertical lines) (b,f,i) the corresponding length distributions for the...

Next, we analyze the case when the cleavage centre D = 15 is between two points where the derivative is equal to — y, and hence the maximum condition can be fulfilled in one point (see Fig. 14.8e). As predicted by theory and confirmed by numerics, the length distribution has a maximum in this case (see Fig. 14.8f). It is noteworthy that the theory in this case works sufficiently also in the case when the cleavage products do not disappear immediately (see Fig. 14.8g). If we believe in the nonmonotonous transport rate function hypothesis [50], this case seems to be the most adequate for protein degradation by the proteasome. In the last case, the cleavage centre is so deep in the proteasome, D = 32, that the maximum condition can be fulfilled nowhere. As expected, the length distribution has no maxima in all cases computed for this relation between the transport function and the geometry of the proteasome. 

When comparing dependencies of the membrane permeability on nitric acid concentrations in Nd transport processes with use of bis-phospho-rilamine 1 solutions (0.1 mol L ) in kerosene and 1,2-dichlorobenzene (Fig. 6.6), one fact draws attention that in the second case this value is about two times higher compared to when using nonpolar kerosene. The diagram shows nonmonotone decrease of values, that reaches 3.6-x 10 m s value for 1.2-dichlorobenzene under nitric acid concentrations 0.5 rnolL and also the diagram shows absence of metal transport when using kerosene. 

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