Nuclear magnetic resonance studies of bovine $\gamma$B-crystallin

Anisotropy of shape and/or interactions play an important role in determining the properties of concentrated solutions of the eye lens protein, $\gamma$B-crystallin, including its liquid-liquid phase transition. We are studying $\gamma$B anisotropic interactions with use of nuclear magnetic resonance (NMR) concentration- and temperature-dependent chemical shift perturbations (CSPs). We analyze two-dimensional heteronuclear spin quantum coherence (HSQC) spectra on backbone nitrogen and attached hydrogen nuclei for CSPs, up to 3 percent volume fraction. Cumulative distribution functions of the CSPs show a concentration and temperature-dependent spread. Many peaks that are highly shifted with either concentration or temperature are close (i) crystal intermolecular contacts (ii) locations of cataractogenic point mutations of a homologous human protein, human $\gamma$D-crystallin, and (iii) charged amino-acid residues. We also discuss the concentration- and temperature-dependence of NMR and quasielastic light scattering measurements of rotational and translational diffusion of $\gamma$B crystallin in solution, affected by interprotein attractions.