Specific Buffer Effects on the Intermolecular Interactions among Protein Molecules at Physiological pH

Abstract

BSA and lysozyme molecular motion at pH 7.15 is buffer-specific. Adsorption of buffer ions on protein surfaces modulates the protein surface charge and thus protein–protein interactions. Interactions were estimated by means of the interaction parameter k D obtained from plots of diffusion coefficients at different protein concentrations (D app = D 0[1 + k D C protein]) via dynamic light scattering and nuclear magnetic resonance. The obtained results agree with recent findings confirming doubts regarding the validity of the Henderson–Hasselbalch equation, which has traditionally provided a basis for understanding pH buffers of primary importance in solution chemistry, electrochemistry, and biochemistry.

Buffer-specific effects arise from ionic dispersion forces

“…The buffer-specific trends shown here in lysozyme zeta potentials have been found also in lysozyme adsorption on silica 8 (in the reverse order citrate 4 phosphate 4 Tris, indicating that a smaller positive lysozyme potential counterintuitively increases adsorption to the negatively charge silica surface). Buffer specificity is also observed in protein diffusivity, 6,10 enzyme activity 11 and pH measurement. 4…”

“…Oscillator weights a i (Å 3 ) and oscillator frequencies o i (eV) for five-mode decompositions of the dynamic electronic polarizabilities in vacuum of buffer and other ions (see eqn(10)). a 0 is the static polarizability at o = 0…”

Interaction of Aqueous Bovine Serum Albumin with Silica Aerogel Microparticles: Sorption Induced Aggregation

“…These ion-specific interactions arise from the Hofmeister series, which is well established in protein systems [ 25 , 26 , 27 ]. The fact that the ζ-potential of silica aerogel is negative even at pH = 3.0 strengthens the idea of the specific sorption of phosphate and acetate anions form the corresponding media.…”

Molecular Mechanistic Insights into the Ionic-Strength-Controlled Interfacial Behavior of Proteins on a TiO2Surface

“…Compared with the addition of strong electrolytes, changing the concentration of the ions in buffer solutions can be a desirable alternative strategy considering their remarkable role in adjusting the ionic strengths. ,, However, compared to the studies on adding strong electrolytes, the work on adjusting buffers has not been sufficiently concerned. The available work deals mainly on how to adjust the buffer ions to achieve different applications at the macroscale, such as separation focusing on chromatography, drug delivery, or controlling the properties of protein molecules in the bulk solution. ,, Very few studies so far have focused on the effect of buffer ions on the complex interfacial behavior of proteins on the solid surfaces at the microscale, especially that on the complex solid surface.…”