Date of Award
2024
Document Type
Open Access Master's Thesis
Degree Name
Master of Science in Chemistry (MS)
Administrative Home Department
Department of Chemistry
Advisor 1
Ashutosh Tiwari
Committee Member 1
Athar Ata
Committee Member 2
Loredana Valenzano-Slough
Abstract
Protein aggregation is a hallmark of neurodegenerative diseases (NDs). Although there has been a greater emphasis in the past decade or more on the correlation between the physicochemical characteristics of aggregates and their cellular toxicity, it is still unclear what specific features of an aggregate render it toxic. To better understand that, there has been a renewed focus on the characterization of unique biochemical and biophysical properties of protein aggregates. Elucidation of these unique characteristics can help to better understand disease pathogenesis in vivo. Furthermore, the lipid-rich nature of the brain sets it apart from all other organs, and numerous studies have suggested that lipid membranes may play an important role in the neurodegenerative process. Isolated brain tissue samples from ND patients show a severe decrease in phospholipid content, which are crucial in structural stability of membranes. Therefore, research on protein aggregation both with and without lipids that are primarily present in membranes may aid in a better understanding of the role these lipids play in the aggregation process. To do so, two well characterized model proteins, hen egg-white lysozyme and human insulin, were used for aggregation studies in vitro. Aggregation of these proteins was characterized under reducing conditions to mimic the reducing environment of the cell as well as under conditions of varied pH and temperature. It was found that the presence of model lipid membranes did not significantly impact aggregate secondary structure or morphology, while reducing conditions and temperature had a greater influence on aggregate characteristics. It's interesting to note that SEM characterization of aggregates revealed that stub surface characteristics may affect aggregate size and shape. This led to a secondary investigation on the impact of stub surfaces on observed aggregate morphology, where we found that unique surfaces did alter the size and structure of aggregates. In summary, the research indicates that temperature, reducing agents, pH, and the surface characteristics of the SEM stub all affect the characteristics of protein aggregates.
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.
Recommended Citation
Hall, Connor J., "A Physicochemical Characterization of Protein Aggregates: Influence of Lipid Membranes and Surfaces", Open Access Master's Thesis, Michigan Technological University, 2024.