Thermodynamics of the Gamma B Crystallin Protein Demonstrated by T1/T2 NMR Experiments

Abstract

Gamma B Crystallin proteins are soluble proteins found in the eye lens which help maintain its transparency; however, over time their structure may mutate due to UV radiation and other environmental stresses causing the proteins to aggregate and develop into cataracts. Using light scattering, nuclear magnetic resonance (NMR) spectroscopy and other protein modeling techniques, our team is attempting to understand the intermolecular interactions of gamma B crystallin proteins that are responsible for this aggregation. We expect to learn the structural and chemical properties that dictate how the proteins interact, as well as the effect of the thermodynamic properties in the fluid mixtures of the eye lens on the crystallin interactions. We expressed the gamma B crystallins in Escherichia coli and isolated them using size exclusion and ion exchange chromatography. The protein was analyzed using various types of NMR experiments, including T1/T2 experiments. The Tau C values, which were derived from these experiments, correlate with a decreased tumbling time; this means that lower Tau C values indicate increased aggregation. Our preliminary results suggest that cold temperatures and high concentrations of our protein increase aggregation levels and the number of attractive intermolecular interactions.Support or Funding InformationNIH EY018249 (G. Thurston)