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

Salis, Andrea

;Cappai, Luca;Carucci, Cristina;Parsons, Drew Francis;Monduzzi, Maura

2020-01-01

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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 kD obtained from plots of diffusion coefficients at different protein concentrations (Dapp = D0[1 + kDCprotein]) 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.