Browsing by Author "Amaris, Althea"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Characterizing mVenus adsorption to photodegraded polyethylene using circular dichroism and fluorescence spectroscopy
    (2022-08) Amaris, Althea
    Due to their versatility and relative cost-effectiveness, plastics as a material have gained increasing popularity and are heavily utilized by almost every major industry in the modern day. Their exponential rate of production coupled with a lack of proper disposal methods, however, have resulted in the global environmental issue of plastic pollution. Upon entering the ecosystem, plastic surfaces can act as a foundation for the formation of microbial communities known as biofilms. An initial key step to biofilm growth is the attachment of bacterial surface proteins onto the polymer. In this study, we examine structural changes of a “hard” model protein in the presence of environmentally relevant plastics. Using the intrinsic probes of the mVenus protein, a model yellow fluorescent protein (YFP), we study its structural response to variably photo-aged polyethylene (PE) through circular dichroism (CD) and tryptophan (W)/YFP-fluorescence spectroscopy. Upon binding to aged PE, mVenus undergoes mild secondary structure rearrangement. Interestingly, a forbidden transition in W-fluorescence is observed, evolving from the interaction between the sole tryptophan in mVenus and the increasingly hydrophilic surface of PE as the polymer is progressively photo-oxidized. The beta barrel and beta sheet structure of mVenus retains the overall stability of the protein, whereas the local structure and turn regions accommodate the protein-polymer interactions based on polymer surface chemistry. We can therefore start to predict that proteins bind variably during the initial docking of cells as the secondary structure behaves distinctly based on the age of the film to which it attaches. The dependence of protein docking on the extent of PE-irradiation reveals that film age, polymer type, and structural stability can either accelerate or inhibit biofilm growth.
  • Thumbnail Image
    Item
    Interdomain Force Dispersion within Spectrin Repeats of Dystrophin and its Influence on Secondary Structure
    (2020-05) Nelson, Eleanore; Amaris, Althea; Nohner, Madison; Olson, Kari; Tigner, Jonathan; Fealey, Michael; Hinderliter, Anne
    Dystrophin is a large protein complex that connects the cytoskeleton to the extracellular matrix and functions to stabilize muscle cells when force is applied. Dystrophin consists of four domains; an actin binding domain (ABD-1), triple helical spectrin domains composed of 24 spectrin repeats (SR’s), and cysteine rich domain, and the C terminal domain. Mutations, even single point mutations, within the dystrophin gene are known to cause muscular dystrophy, a condition characterized by progressive weakness of the muscles. The fact that single point mutations can result in muscular dystrophy support the idea the domains must communicate with each other. It has been hypothesized that dystrophin exhibits negative interdomain coupling mechanism, meaning that as force is dispersed across the domains, domains destabilize each other and adopt multiple conformations. This negative coupling mechanism is being tested on the spectrin repeats of dystrophin and the actin binding domain. This presentation discusses the data analysis method used to calculate free energy using differential scanning calorimetry, the conclusions drawn thus far from data obtained, and analyzes circular dichroism data to predict secondary structures of the constructs.