Cataracts are one of the leading causes of blindness in the world. Cataracts can occur when proteins (known as “crystallins”) in the cytoplasm of the eye lens phase separate or associate, creating local fluctuations in the refractive index of the lens. Bovine γB-crystallin is analogous (in sequence, structure, and function) to the human γD-crystallin and can be isotopically labeled during growth with 13C and 15N when expressed in Escherichia coli. In this work, the two most important Brownian motions, rotational and translational diffusion, were measured under various temperatures and concentrations in an effort to better understand the intermolecular interactions and behavior of γB-crystallins in solution. Rotational Correlation Times (τc) were estimated from T1/T2 nuclear magnetic resonance (NMR) data, and pulsed field gradient NMR was used to measure translational diffusion. Preliminary results suggest that bovine γB-crystallins associate more with increased protein concentration and/or decreased temperatures. Both single and double exponential decays were used to fit the T1 data, and the corresponding τc values were compared. Additionally, the average hydrodynamic radii of the molecules were approximated using the calculated τc values, which supports our hypothesis that the proteins are indeed associating. Diffusion coefficients were also measured at various concentrations, with preliminary results indicating that as concentration increases, diffusion coefficients decrease, supporting the theory that even small increases in protein concentration result in association of the γB-crystallins.
Department, Program, or Center
School of Chemistry and Materials Science (COS)
Lea Vacca Michel
Fadden, Aaron Thomas, "NMR Studies of Translational and Rotational Diffusion of a Phase Separating Eye Lens Protein: Bovine γB-crystallin" (2019). Thesis. Rochester Institute of Technology. Accessed from
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