Ionic strength binding calculations

We resume the problem discussed in Example 2.2 and solve the same problem, but now we correct for electrostatic effects. Sumarizing the problem Calculate the pH dependence of the binding of a) a metal ion Me2+, and b) of a ligand A to a hydrous oxide, SOH, and compare the effect of a charged surface at an ionic strength I = 0.1. A specific surface area of 10 g m 2 10 4 mol surface sites per gram ( 6 sites nnrr2) concentration used 1 g e-1 (10 4 mol surface sites per liter solution). As before (Example 2.2) the surface complex formation constants are log Kj = -1 and log K = 5, respectively. 

For a given temperature the standard state is at zero ionic strength. The constant observed experimentally at finite ionic strengths would be considered apparent, A biochemist would call such a constant intrinsic. The presence of interfering ions (H and K ) which form H and K chelates of ATP by binding to ATP would be handled by calculations involving the corresponding equilibria. 

These tables can be used to calculate ArG ° and ATH ° at pH 7 and ionic strengths of 0, 0.10, and 0.25 M or at ionic strength 0.25 M and pHs of 5, 6, 7, 8, and 9 for any reaction for which all the reactants are in these tables. They can also be used to calculate standard apparent reduction potentials. The species data can be used to calculate average bindings of hydrogen ions by reactants. Mathematica programs for carrying out these calculations are provided. 

Calculate the fractional saturation YT of the tetramer of human hemoglobin with molecular oxygen using the equilibrium constants determined by Mills, Johnson, and Akers (1976) at 21.5 °C, 1 bar, pH 7.4, [Cl"] = 0.2 M and 0.2 M ionic strength. Make the calculation with the Adair equation and also by using the binding polymomial YT. 

FIGURE 17 Dynamic binding capacity (DBC) for human polyclonal IgG of a HCIC column as a function of the pH (A) and of the ionic strength (B) of the medium. Determinations were performed by frontal analysis and calculations done at 10% breakthrough. IgG concentration was I mg/mL of initial solution linear flow rate was 75 cm / hr. 

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