Potentiometric titration and conformation of synthetic and natural polyelectrolytes

Abstract

From the analysis of the potentiometric titration data of polyelectrolytes, we can obtain the electrostatic free energy of the macromolecules. Therefore, potentiometric titration is a useful experimental procedure to study the conformation and conformational change of macromolecules. A few examples of the application of potentiometric titration to the studies on polypeptides, protein and DNA are discussed. When the potentiometric titration method is not applicable, the numerical solution of the Poisson-Boltzmann equation without use of the Debye-Hflckel approximation may be employed to estimate the electrostatic potential at the surface of macromolecules. To confirm the reliability in the values thus estimated without experiments and in the values of the electrostatic free energy calculated from the surface potential, the calculated potentiometric titration data are compared with experimental data of various polyelectrolytes and proteins. The relationship between potentiometric titration data and conformations of stereoregular polyelectrolytes is also discussed.

On the Complexation of Cd(II) Ions with Polyacrylic Acid

“…where G represents the activity coefficient quotient ( (30,31). An increase in a produces a stronger free M Z/ ion in the bulk solution phase by the use of the DpK term determinable potentiometrically.…”

“…[17] are ion to a polyion can generally be expressed as (2,29,31), based on the polyelectrolyte phase volume.…”

The Electrostatic Origin of Low‐Hydration Polymorphism in DNA

“…As mentioned before two different types of polyions can be considered polyions that i) undergo or ii) do not undergo conformational changes 42. Most polyelectrolytes are water soluble due to the fact that the hydrophobicity of the polymer backbone is overcompensated by the hydrophilic nature of the charged groups.…”

Viscosity and potentiometric measurements of poly(L‐histidyl‐L‐alanyl‐α‐L‐glutamic acid) and poly(L‐lysyl‐L‐alanyl‐α‐L‐glutamic acid)

“…(1) may be simplified to If K2/K1 is less than 1 (e.g., equal to or less than 0.01) then Eq. (4) becomes Equation (5) is a quadratic whose solution is (6) Assuming that the average charge on the macromolecules is described (7) (at extreme pH's this assumption may not be valid as counterions would lower z), then -log10 X = 0.868 wn(a -0.5) (8) Incorporating Eq. (8) into the logarithmic form of Eq.…”