Dynamic affinity plot

Thus, a plot of log K vs v (dynamic affinity plot) defines two regions demarcated by a line with slope log(A) and intercept log(A). The line originates at the point A on the ordinate axis and passes through the point defined by the parameters K and v of the species. The region above the affinity line includes all solutes which will displace the solute when traveling at a velocity characterized by A. Conversely, the solutes in the region below the affinity line will be displaced by the solute under these conditions. 

A dynamic affinity plot is presented in Fig. 10 for the proteins bovine and horse heart cytochrome c on a cation-exchange column. As one moves in a counterclockwise direction, the dynamic affinity of the molecule increases. The dynamic affinity plot provides an easy method of determining the order of elution in a displacement experiment as is shown in Fig. 4B. 

FIGURE 10 Dynamic affinity plot for cytochrome c s from bovine and horse heart and BAEE under the condition described in Fig. 4B. (Kundu et al.4i)... 

While the dynamic affinity plot provides a simple graphical representation of the order of elution in a displacement, that order is restricted to the particular operating conditions chosen for that experiment (i.e., for a specified value of A). In contrast, the affinity ranking plot can show the variation of the dynamic affinity of a molecule over a range of A values. To enable this comparison, the dynamic affinity A (which is the criterion for displacement) can be plotted against the displacer partition ratio A (which is the operating variable for displacement). The equation for such a plot can be determined by rearrangement of Eq. (6) as... 

For a given A value, the higher the A value, the better the displacer under those operating conditions. As expected, an increase in the A value as one moves along the x axis (which corresponds to lower displacer concentrations or lower salt concentrations) results in a decrease in the value of the dynamic affinity (A). This plot has been employed to rank the relative efficacy of displacers51,54 and to provide insight into the important structural features of low molecular weight displacers (Section VII). 

Adsorption for gas purification comes under the category of dynamic adsorption. Where a high separation efficiency is required, the adsorption would be stopped when the breakthrough point is reached. The relationship between adsorbate concentration in the gas stream and the solid may be determined experimentally and plotted in the form of isotherms. These are usually determined under static equilibrium conditions but dynamic adsorption conditions operating in gas purification bear little relationship to these results. Isotherms indicate the affinity of the adsorbent for the adsorbate but do not relate the contact time or the amount of adsorbent required to reduce the adsorbate from one concentration to another. Factors which influence the service time of an adsorbent bed include the grain size of the adsorbent depth of adsorbent bed gas velocity temperature of gas and adsorbent pressure of the gas stream concentration of the adsorbates concentration of other gas constituents which may be adsorbed at the same time moisture content of the gas and adsorbent concentration of substances which may polymerize or react with the adsorbent adsorptive capacity of the adsorbent for the adsorbate over the concentration range applicable over the filter or carbon bed efficiency of adsorbate removal required. 

The dynamics were run for several concentrations of substrate and variations in the Pc values. Initial velocities of the reaction were recorded. The Michaelis-Menten model was observed and characteristic Lineweaver-Burk plots were found from the model. Systematic variation of the lipophilicity of substrates and products showed that a lower affinity between a substrate and water leads to more of the S —> P reaction at a common point along the reaction progress curve. This influence is greater than that of the affinity between the substrate and the enzyme. The study created a model in which the more lipophilic substrates are more reactive. The water-substrate affinity appears... 

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