pH dependence of charge multipole moments in proteins

Abstract

Electrostatic interactions play a fundamental role in the structure and function of proteins. Due to ionizable amino acid residues present on the solvent-exposed surfaces of proteins, the protein charge is not constant but varies with the changes in the environment -- most notably, the pH of the surrounding solution. We study the effects of pH on the charge of four globular proteins by expanding their surface charge distributions in terms of multipoles. The detailed representation of the charges on the proteins is in this way replaced by the magnitudes and orientations of the multipole moments of varying order. Focusing on the three lowest-order multipoles -- the total charge, dipole, and quadrupole moment -- we show that the value of pH influences not only their magnitudes, but more notably and importantly also the spatial orientation of their principal axes. Our findings imply important consequences for the study of protein-protein interactions and the assembly of both proteinaceous shells and patchy colloids with dissociable charge groups.

15 pages, 6 figures; 12 pages and 12 figures of Supporting Material; accepted for publication in Biophysical Journal

References in corpus (2)

• Interaction of charged patchy protein models with like-charged polyelectrolyte brushes
• Symmetry effects in electrostatic interactions between two arbitrarily charged spherical shells in the Debye-Hückel approximation

Cited by in corpus (10)

• Charge Regulation with Fixed and Mobile Charges
• Electrostatic interaction between SARS-CoV-2 virus and charged electret fibre
• Charge Regulating Macro-ions in Salt Solutions: Screening Properties and Electrostatic Interactions
• Anomalous Multipole Expansion: Charge Regulation of Patchy, Inhomogeneously Charged Spherical Particles
• Charge regulation of colloidal particles in aqueous solutions
• From discrete to continuous description of spherical surface charge distributions
• Varieties of charge distributions in coat proteins of ssRNA+ viruses
• Anisotropic DLVO-like interaction for charge patchiness in colloids and proteins
• Symmetry breaking of dipole orientations on Caspar-Klug lattices
• The Casimir free energy of peptide films on a silicon substrate: Impact of dielectric-to-metal transition in silicon and nanoparticles in peptide