Biophysics Commons^™

Investigation Of Early Complex Formation Of Huntingtin Protein With And Without Lipids, Alyssa R. Stonebraker

Graduate Theses, Dissertations, and Problem Reports (ETD)

Huntington’s disease (HD) is a fatal neurodegenerative disease caused by the expansion of the polyglutamine (polyQ) domain of the huntingtin protein (htt). The expansion of the polyQ domain beyond a threshold of approximately 35 repeats triggers complex toxic aggregation mechanisms and results in altered interactions between htt and lipid membranes. Many factors modulate these processes. One such modulator includes sequences flanking the polyQ domain, most notably the first 17 amino acids at the N-terminus of the protein (Nt17), and environmental factors including the presence of membranous structures. Nt17 has the propensity to form an amphipathic a-helix in the presence of …

Multiscale Molecular Modeling Studies Of The Dynamics And Catalytic Mechanisms Of Iron(Ii)- And Zinc(Ii)-Dependent Metalloenzymes, Sodiq O. Waheed

Dissertations, Master's Theses and Master's Reports

Enzymes are biological systems that aid in specific biochemical reactions. They lower the reaction barrier, thus speeding up the reaction rate. A detailed knowledge of enzymes will not be achievable without computational modeling as it offers insight into atomistic details and catalytic species, which are crucial to designing enzyme-specific inhibitors and impossible to gain experimentally. This dissertation employs advanced multiscale computational approaches to study the dynamics and reaction mechanisms of non-heme Fe(II) and 2-oxoglutarate (2OG) dependent oxygenases, including AlkB, AlkBH2, TET2, and KDM4E, involved in DNA and histone demethylation. It also focuses on Zn(II) dependent matrix metalloproteinase-1 (MMP-1), which helps …

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 …

Quantum Computations And Molecular Dynamics Simulations: From The Fundamentals Of Antimicrobial Resistance To Neurological Diseases, Angel Tamez

Electronic Theses and Dissertations

Biophysical phenomena are modeled using a combination of quantum and classical methods to interpret and supplement three distinct and diverse problems in this dissertation. In the first project, decarboxylation reactions are ubiquitous across chemical and biological disciplines, yet the origin of non-catalytic solvent effects remains elusive. Specific solvent structure and energetics have not been well described for the monoanion of malonate, nor corrected from the gas-phase charge-assisted intramolecular hydrogen bond model known as “pseudochair”. In the aqueous phase, a low-lying energy conformer known as the “orthogonal conformation” is computed to be preferred by a three-water cluster of hydrogen bonding over …

Dynamics Of Nucleosome Assembly Characterized By Atomic Force Microscopy, Tommy Stormberg

Theses & Dissertations

Nucleosomes are the basic repeating unit defining the assembly and function of chromatin. Understanding the fundamental mechanisms of nucleosome structure and dynamics is critical to elucidating the chromatin assembly process. This dissertation describes my work in elucidating the role of different factors that drive the nucleosome dynamics.

In my first study, we characterized, for the first time, the effect of sequence on nucleosome assembly. We then characterized the role of internucleosomal interactions, discovering a critical role internucleosomal interactions in the assembly of higher order structures.

Based on the previous study and literature regarding histone tails, we hypothesized the histone H4 …

Structural And Biochemical Studies Of Three Enzymes Involved In Amino Acid Metabolism To Develop Novel Drugs, Yahani Pankaja Jayasinghe Arachchige

Theses & Dissertations

Intrinsic drug resistance in bacteria predates the clinical use of antibiotics. Additionally, heterogeneous metabolic states and the ability of many bacteria to form biofilms further enhances bacterial survival during infection and exacerbates treatment challenges. This necessitates the identification of novel drugs against new drug targets. These studies focus on the development of compounds targeting enzymes in Mycobacterium tuberculosis (Mtb) and Staphylococcus aureus that avoid intrinsic antibiotic defenses. The Mtb-encoded homoserine transacetylase enzyme (HTA) catalyzes the first step of the methionine biosynthesis pathway that produces methionine and S-adenosyl methionine. These compounds are shown to be essential for both dormant …

Designing And Synthesizing A Warhead-Fragment Inhibitory Ligand For Ivyp1 Through Fragment-Based Drug Discovery, Samuel Moore

Symposium of Student Scholars

Fragment-based drug discovery (FBDD) is a powerful tool for developing anticancer and antimicrobial agents. Within this, magnetic resonance spectroscopy (NMR) provides a comprehensive qualitative and quantitative approach to screening and validating weak and robust binders with targeted proteins, making NMR among the most attractive strategies in FBDD. Inhibitor of vertebrate lysozyme (Ivyp1) of P. aeruginosa serves as an excellent target because of its active cellular location and implications in clinical prognosis for cystic fibrosis and immunocompromised patients. This study uses current NMR and biophysical techniques to develop a covalent, fragment-linked warhead inhibitor for Ivyp1 through synthetic methods, warhead linking, and …

Cell Division Dynamics Of Escherichia Coli In Extreme Environments, Steven P. Murray

Graduate Theses and Dissertations

Life is remarkable in how resilient it can be. Many organism, classified as ex- tremophiles, can not only survive in extreme environments, but they can thrive in them. In the search for extraterrestrial life, the best candidates to harbor life exist with some kind of extreme condition. Europa, for example, is a favorite for the possibility of accommodating life as we know it within our solar system. Thought there is believed to be a liquid ocean under its icy surface, this habitat would be under immense pressures and high salinity. To best know where to look for extraterrestrial life, it …

The Metabolic Change Of Lipid Species In Stam Mice With Hepatocellular Carcinoma, Devin J. Peart

UNLV Theses, Dissertations, Professional Papers, and Capstones

Primary liver cancer hepatocellular carcinoma (HCC) is the second leading cause of cancer death worldwide. In the US, primary liver cancer is the most rapidly increasing type of cancer due to increases in hepatitis B and C and the continued trend of greater and greater percentages of the population suffering from obesity, diabetes mellitus and metabolic syndrome. The prognosis for this disease is poor, with a 5-year survival rate of 26% as compared to only 2% when the cancer is metastatic. Unfortunately, current strategies for early detection of HCC, including routine CT imaging or alpha-fetoprotein biomarker, are suboptimal and tend …

Comparative Analysis Of Conformational Transition Pathways In Homologous Proteins, Dylan Sebastien Ogden

Graduate Theses and Dissertations

Molecular dynamics (MD) simulations are routinely used to study the dynamics of proteins. However, conventional MD limited to the sampling of local conformational changes as the functionally important conformational transitions of proteins often extend beyond the timescales of the simulations employed, for example, membrane transport proteins. We have determined the combination of multiple MD based techniques that allows for a rigorous characterization of energetics and kinetics of large-scale conformational changes in membrane proteins. The methodology is based on biased, nonequilibrium collective variable based simulations including nonequilibrium pulling, string method with swarms of trajectories, bias-exchange umbrella sampling, and rate estimation techniques. …

Modulation Of Alpha-Crystallin-Membrane Association By Phospholipid Acyl Chain Length And Degree Of Unsaturation, Geraline Trossi-Torres

Boise State University Theses and Dissertations

Cataract is the leading cause of blindness worldwide. The only treatment for cataracts is the surgical removal of the cataractous lens and the replacement of an intraocular lens. With less availability of treatment and low income, the visual damage caused by cataracts can go untreated. The cataract may develop again after surgery, such as posterior capsule opacification. With age and cataracts, α-crystallin, a significant protein of the mammalian eye lens, is progressively associated with the eye lens membrane. The primary association sites of α-crystallin with the membranes are phospholipids. However, it is unclear if phospholipids’ acyl chain length and degree …

Case 59: Inhibition Of Enzymes Involved In Steroid Synthesis: Implications In Diabetes Treatment, Dr. Kathleen Cornely

Chemistry & Biochemistry Case Studies

Drugs used to increase insulin sensitivity may also inhibit enzymes involved in steroid synthesis. Prior to this investigation, it was uncertain whether the drugs inhibited the enzymes directly or whether the decrease in androgen synthesis observed during treatment was a secondary effect.

Ferrocenium Salt Aided Substitution Reactions And Synthesis Of Glycosylated Curcumin Derivatives, Deva Saroja Talasila

Dissertations

Organic synthesis has been significantly advanced with the employment of transition metal complexes. The discovery of transition metal catalysts provided the synthetic community with powerful tools for accelerating reactions and making them more selective and efficient. Many chemical reactions do not happen without a catalyst.

Iron-based catalysts have several advantages for the chemical industry because it is a non-toxic and ecologically friendly metal. Our group previously found that ferrocenium cations with a 3+ oxidation state of iron-catalyzed propargylic substitution reactions at low temperatures. The sandwich structure of ferrocenes allows substituents to be introduced on the cyclopentadienyl rings, which allows for …

Regulation Of Tissue Mechanics And Adherens Junctions By Small Gtpase Rhoa During Drosophila Embryogenesis, Hanqing Guo

Dartmouth College Ph.D Dissertations

Actomyosin contractility plays an important role at both the cell and tissue level during developments. In this study, we developed an optogenetic tool that can acutely inhibit actomyosin contractility by targeting its main activator Rho1. This optogenetic tool can achieve myosin inhibition within one minute and thus enable further dissection of actomyosin function in development. In my first two projects, I used Drosophila mesoderm invagination (also known as ventral furrow formation) as a model to study epithelial folding, a fundamental mechanism for constructing complex 3D tissues. Apical constriction mediated by actomyosin contractility is a common mechanism for epithelial folding. However, …

Biochemical And Biophysical Characterization Of Replicative Helicase Loading By Vibrio Cholerae Dcia, Crystal Structure Of A Monoclonal Antibody Bound To A C-Terminal Fragment Of Ebna-1 From Epstein Barr Virus, Nicholas Gao

Dissertations, Theses, and Capstone Projects

DNA replication initiation is mediated by the binding of an initiator protein to genomic origins of replication to begin the process of loading replicative helicases onto the genome. The loading of the helicase requires the action of an accessory protein, named a “loader”. Studies on well-characterized loaders have outlined how the bacterial DnaB replicative helicase is loaded via mechanisms of “Ring-Breaking” by E. coli DnaC (EcDnaC)/protein P from bacteriophage lambda (LP) and “Ring-Making” by B. subtilis DnaI. Mounting evidence points to a recently discovered candidate loader, named DciA, that shows a more widespread distribution throughout bacteria than DnaC and DnaI …

Co-Twin Relationship Quality As A Moderator Of Genetic And Environmental Factors On Urinary Cortisol Levels Among Adult Twins, Joseph A. Schwartz, Scott Jessick, Jessica L. Calvi, Douglas A. Granger

Athletic Performance Research

Previous research has indicated that genetic and environmental factors shape physiological activity. Cortisol levels, in particular, have received significant attention, with studies indicating substantive heritability estimates across various sampling techniques. A related line of research has indicated that genetic and environmental factors that explain variability in cortisol levels may vary across context and experiences by way of gene-environment interactions (G×Es). Despite these findings, a limited number of studies have examined the extent to which interpersonal relationships may operate as a moderator. The current study focused on co-twin relationship quality as a source of moderation, as twins are more likely to …

Role Of Ligand Architecture On Collective Cell Invasion, Amrit Bagchi

McKelvey School of Engineering Graduate Student Theses & Dissertations

Epithelial cell collectives utilize extra-cellular matrix (ECM) fibers to undergo collective migration critical in regeneration, repair and cancer metastasis. However, very little is known about the various factors which determine the ability of cellular collectives to utilize ECM fibers to undergo these critical processes in-vivo. First part of the dissertation focusses on understanding how cell collectives exploit specific properties, like stiffness and fiber length to undergo collective streaming. It is also unclear how cellular forces, cell-cell adhesion, and velocities are coordinated within streams. To independently tune stiffness and collagen fiber length, we developed new hydrogels and discovered invasion-like streaming of …

Amyloid Fibril Formation And Polymorphism : A Critical Role Of Sulfur-Containing Amino Acid Residues, Tatiana Quiñones-Ruiz

Legacy Theses & Dissertations (2009 - 2024)

Protein aggregation that results in the formation of amyloid fibrils has been linked to many neurodegenerative disorders, including Alzheimer’s disease and Parkinson’s disease. The sulfur atoms in methionine (Met) and cysteine (Cys) residues of proteins can be readily oxidized, significantly affecting their properties. Oxidation of sulfur-containing amino acids has recently been shown to affect protein fibrillation. This work presents novel findings on Cys and Met redox reactions that are related to the formation of amyloid fibrils and on the polymorphism of a model fibrillogenic protein, hen egg white lysozyme (HEWL). Biophysical techniques including Raman spectroscopy, atomic force microscopy, electron paramagnetic …

Modeling Electrostatics In Molecular Biology And Its Relevance With Molecular Mechanisms Of Diseases, Mahesh Koirala

All Dissertations

Electrostatics plays an essential role in molecular biology. Modeling electrostatics in molecular biology is complicated due to the water phase, mobile ions, and irregularly shaped inhomogeneous biological macromolecules. This dissertation presents the popular DelPhi package that solves PBE and delivers the electrostatic potential distribution of biomolecules. We used the newly developed DelPhiForce steered Molecular Dynamics (DFMD) approach to model the binding of barstar to barnase and demonstrated that the first-principles method could also model the binding. This dissertation also reflects the use of existing computational approaches to model the effects of Single Amino Acid Variations (SAVs) to reveal molecular mechanisms …

Habitability, And Evolution Of Microorganisms Under Extreme Conditions, Azarin Yazdani

Graduate Theses and Dissertations

The choice of a solvent determines the possible biochemistry of life. Life on Earth is based on carbon biochemistry and has evolved in an environment with water as a solvent. As a polar solvent abundant on Earth, water has unique physical properties, including a large range of liquidity and low viscosity, making it a very good solvent for terrestrial life. Liquids other than water are abundant in the universe, and the chemical nature of these liquids might lead to different chemistries of life. In the first chapter, we review the main characteristics of a good solvent, and then we use …