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Full-Text Articles in Biophysics

Lipid Binding Properties Of Huntingtin As A Novel Therapeutic Target, Chathuranga Siriwardhana Jan 2023

Lipid Binding Properties Of Huntingtin As A Novel Therapeutic Target, Chathuranga Siriwardhana

Graduate Theses, Dissertations, and Problem Reports

As protein aggregation is the defining hallmark of all amyloid diseases, a common therapeutic strategy is to develop molecules that inhibit aggregation. However, this approach has yielded limited success. Many amyloid proteins directly interact with lipid membranes. These interactions promote distinct aggregation pathways and often result in membrane damage leading to toxicity. As a result, directly targeting the ability of amyloids to bind lipid membranes represents a novel therapeutic strategy. As a proof of principle, the interaction between lipid membranes and mutant huntingtin protein (htt) aggregates was used to test this strategy. Mutant htt containing an expanded polygulatmine (polyQ) domain …


Interactions Of Amyloid Peptides With Lipid Membranes, Yanxing Yang Dec 2022

Interactions Of Amyloid Peptides With Lipid Membranes, Yanxing Yang

Dissertations

The aggregation of amyloid proteins into fibrils is a hallmark of several diseases including Alzheimer’s (AD), Parkinson’s, and Type II diabetes. This aggregation process involves the formation of small size oligomers preceding the formation of insoluble fibrils. Recent studies have shown that these oligomers are more likely to be responsible for cell toxicity than fibrils. A possible mechanism of toxicity involves the interaction of oligomers with the cell membrane compromising its integrity. In particular, oligomers may form pore-like structures in the cell membrane affecting its permeability or they may induce lipid loss via a detergent-like effect. This dissertation aims to …


Huntingtin Aggregation At Interfaces Associated With Membranes And Organelles, Adewale Vincent Adegbuyiro Jan 2021

Huntingtin Aggregation At Interfaces Associated With Membranes And Organelles, Adewale Vincent Adegbuyiro

Graduate Theses, Dissertations, and Problem Reports

Huntington’s Disease (HD) is a genetic neurodegenerative disease caused by the expansion of polyglutamine (polyQ) domain within the first exon (exon1) of the huntingtin (htt) protein. Due to this mutation within the polyQ domain, htt aggregates into various toxic species such as oligomers, fibrils, and other amorphous aggregates. While the aggregation of htt strongly correlates with polyQ length, other factors, e.g. interaction with membranes or organelles and posttranslational modifications (PTMs), modulate aggregation. The first 17 N-terminal amino acids (Nt17) that precede the polyQ in htt-exon1 enhances aggregation and facilitated binding of htt to membranous organelles, promoting morphological changes and disfunction. …


Structure And Thermodynamics Of Polyglutamine Peptides And Amyloid Fibrils Via Metadynamics And Molecular Dynamics Simulations, Riley Workman Aug 2018

Structure And Thermodynamics Of Polyglutamine Peptides And Amyloid Fibrils Via Metadynamics And Molecular Dynamics Simulations, Riley Workman

Electronic Theses and Dissertations

Aggregation of polyglutamine (polyQ)-rich polypeptides in neurons is a marker for nine neurodegenerative diseases. The molecular process responsible for the formation of polyQ fibrils is not well understood and represents a growing area of study. To enable development of treatments that could interfere with aggregation of polyQ peptides, it is crucial to understand the molecular mechanisms by which polyQ peptides aggregate into fibrils. Many experimental techniques have been employed to probe polyQ aggregation, however, observations from these studies have not lead to a unified understanding of the properties of these systems, instead yielding competing, fragmented theories of polyQ aggregation. This …


Mechanism And Development Of Peptide-Based Inhibitors To Human Islet Amyloid Polypeptide (Hiapp) Self-Assembly, Jayson Vedad May 2018

Mechanism And Development Of Peptide-Based Inhibitors To Human Islet Amyloid Polypeptide (Hiapp) Self-Assembly, Jayson Vedad

Dissertations, Theses, and Capstone Projects

Amyloid fibrils formed by of hIAPP1-37 (also known as amylin) has been linked to type-II diabetes mortalities and its formation was found to be related to the three aromatic residues in hIAPP1-37. In this dissertation, the role of aromatic amino acids, particularly that of Phe-23, and its various interactions to the self-assembly of human islet amyloid polypeptide (hIAPP)22-29 were investigated. Using a variety of spectroscopic techniques with emphasis to vibrational spectroscopy (FT-IR and Raman spectroscopies) in conjunction with computational methods, different factors leading to aggregation as well as its inhibition were identified. Among the driving forces …


A Mechanistic Understanding Of Self-Propagating Amyloid-Β Oligomer Conformations In Alzheimer Disease, Dexter Nathanael Dean May 2018

A Mechanistic Understanding Of Self-Propagating Amyloid-Β Oligomer Conformations In Alzheimer Disease, Dexter Nathanael Dean

Dissertations

Alzheimer disease (AD) is a fatal neurodegenerative disorder characterized by the widespread deposition of proteinaceous plaques abundant in amyloid-β (Aβ) aggregates. Although the plaques mainly contain high molecular weight, insoluble Aβ fibrils, the low molecular weight soluble aggregates called oligomers have been shown as the primary toxic species responsible for synaptic dysfunction and neuronal loss in AD. The process of aggregation is nucleation-dependent, but also highly stochastic and inhomogeneous resulting in biophysically diverse assemblies. Recent advances in the field indicate a potential correlation between the phenotypic diversity observed in AD subtypes and aggregate polymorphism. Therefore, understanding the molecular mechanisms which …


Structure And Stability Of Amyloid Fibrils Studied By Advanced Vibrational Spectroscopy, Marudachalam Shanmugasundaram Jan 2015

Structure And Stability Of Amyloid Fibrils Studied By Advanced Vibrational Spectroscopy, Marudachalam Shanmugasundaram

Legacy Theses & Dissertations (2009 - 2024)

Protein misfolding often leads to the formation of refractory protein aggregates like amyloid fibrils. These fibrils possess a highly ordered structure and are implicated in over 25 severe diseases including Alzheimer’s, Parkinson’s and prion diseases. This work was focused on understanding the morphology and conformation of amyloid fibrils and their stability after formation. The deconstruction of fibrils as well as other aggregates like inclusion bodies under mild conditions was also investigated using Archaeal chaperones.


Amylin Structure, Aggregation, And Pancreatic Β Cell Toxicity, Sharadrao Patil Dec 2014

Amylin Structure, Aggregation, And Pancreatic Β Cell Toxicity, Sharadrao Patil

MCB Articles

In most type 2 diabetes patients, amyloid plaques have been found juxtaposed with membranes of pancreatic β-cells. These plaques are composed of amyloid fibrils of the 37 residue endocrine hormone amylin and cause distinct changes in cell membrane morphology associated with the destruction of β-cells. Research is still ongoing to identify the toxic species involved and the mechanisms by which mature fibrils or oligomers cause cytotoxicity. The projects undertaken were designed to study the molecular structural features of amylin, mechanism of amyloid aggregation and, to develop cytotoxicity inhibitors. We determined the structure of human amylin bound to SDS micelles using …