Jonathan Tigner

The human muscle protein Dystrophin is an essential structural protein that protects the cytoplasmic membrane from mechanical strain. Dystrophin mediates this mechanical strain on cell membranes and prevents the cells from rupturing. Better understanding of Dystrophin is crucial since it is known that mutations in Dystrophin are responsible for the two leading types of Muscular Dystrophy: Duchenne and Becker. The mechanism of how Dystrophin dissipates mechanical strain is still unknown, and the Hinderliter lab suggests it does this, in part, through a mutual destabilization of spectrin repeats. 24 of these spectrin repeats make up the central rod domain of Dystrophin, with spectrin 17 through 19 being the focus of this research. To test our hypothesis, energetic trends in stability, as measured by free energy of stability, were measured using fluorescence spectroscopy (FM, FLT), circular dichroism (CD), and differential scanning calorimetry (DSC). These methodologies have been used with thermal denaturation to monitor protein unfolding after being fit to a two-state model of unfolding. This analysis is then used to calculate enthalpy of unfolding (ΔH), melting temperature (Tm), heat capacity (ΔCp), and in turn, free energy of unfolding (ΔG). Data collected has shown trends in free energies consistent with our hypothesis of mutual spectrin destabilization, and further investigation is currently underway.