Biophysics Commons^™

Development Of Fluorescence Based Approaches To Understand Astrocyte Biology In The Context Of Nicotine And Nicotinic Receptor Activity, Surya P. Aryal

Theses and Dissertations--Chemistry

Smoking and tobacco use (STU) is a major global health problem and worldwide more than six million people die due to tobacco related diseases each year. Although majority of smokers try to quit smoking several times in their life, traditional therapeutic approaches, which focus only on neuronal cells, have a very low success rate. Understanding the effect of nicotine on glial cells, synaptic communication and blood vasculature in the brain can provide further insights on the neurobiology of substance abuse and can potentially help to design better therapeutic approaches. Glial cells are non-excitable cells in the brain which do not …

Elucidating The Proteasomal Regulatory Mechanism Of Proteasome Activator Pa28Γ /Regγ, Taylor Ann Thomas

Graduate Theses, Dissertations, and Problem Reports (ETD)

Virtually all cellular processes are precisely regulated by the proteasome which is the primary enzyme responsible for the degradation of misfolded, damaged, or no longer necessary soluble proteins. To prevent any untimely degradation of these target protein substrates and protect the cell, the proteasome is tightly regulated via adaptor proteins, known as proteasomal regulators. There are many classes of proteasomal regulators each with their own unique structures, functions, and effects on protein degradation through the proteasome. One such class is the 11S family of proteasomal regulators which are also referred to as PA26/28, or REG. The 11S family are ATP-independent …

Multilevel Computational Investigation Into The Dynamics And Reaction Mechanisms Of Non-Heme Iron And 2-Oxoglutarate Dependent Enzymes, Shobhit Sanjeev Chaturvedi

Dissertations, Master's Theses and Master's Reports

Computational chemistry methods have been extensively applied to investigate biological systems. This dissertation utilizes a multilevel computational approach to explore the dynamics and reaction mechanisms of two groups of enzymes belonging to non-heme Fe(II) and 2-oxoglutarate (2OG) dependent superfamily – histone lysine demethylases from class 7 and ethylene forming enzyme (EFE). Chapter 2 uncovers the role of conformational dynamics in the substrate selectivity of histone lysine demethylases 7A and 7B. The molecular dynamics (MD) simulations of the two enzymes revealed the importance of linker flexibility and dynamics in relative orientations of the reader (PHD) and the catalytic (JmjC) domains. Chapter …

High-Resolution Cryo-Electron Microscopy Structure Of Photosystem Ii From The Mesophilic Cyanobacterium, Synechocystis Sp. Pcc 6803, Christopher J. Gisriel, Jimin Wang, Jinchan Liu, David A. Flesher, Krystle M. Reiss, Hao-Li Huang, Ke R. Yang, William H. Armstrong, M. R. Gunner, Victor S. Batista, Richard J. Debus, Gary W. Brudvig

Publications and Research

Photosystem II (PSII) enables global-scale, light-driven water oxidation. Genetic manipulation of PSII from the mesophilic cyanobacterium Synechocystis sp. PCC 6803 has provided insights into the mechanism of water oxidation; however, the lack of a highresolution structure of oxygen-evolving PSII from this organism has limited the interpretation of biophysical data to models based on structures of thermophilic cyanobacterial PSII. Here, we report the cryo-electron microscopy structure of PSII from Synechocystis sp. PCC 6803 at 1.93-Å resolution. A number of differences are observed relative to thermophilic PSII structures, including the following: the extrinsic subunit PsbQ is maintained, the C terminus of the …

The Phase Behavior Of Ubqln Proteins And Implications For Protein Quality Control, Yiran Yang

Dissertations - ALL

The ubiquitin-proteasome system (UPS) and autophagy are essential pathways for maintaining protein quality control (PQC) in cells. Misfolded proteins and large aggregates are cleared by UPS and autophagy signaled by ubiquitin (Ub) or polyubiquitin (polyUb) chains. Shuttle proteins facilitate cargo transporting by interacting with both ubiquitin and degradation machineries. Previously, our lab discovered that the shuttle protein Ubiquilin-2 (UBQLN2) is recruited to stress granules in cells and undergoes liquid-liquid phase separation (LLPS) in vitro. LLPS is a biophysical process by which proteins separate themselves from the surrounding aqueous solution by forming protein-rich droplets. The overarching goals of this work are …

Direct Single Molecule Imaging Of Enhanced Diffusion For Enzymes And Enzyme-Conjugated Dna Origami, Mengqi Xu

Dissertations - ALL

Enzymes have been shown to diffuse faster in the presence of their substrates. Recently, we revealed new insights into this process of enhanced diffusion using single-particle tracking (SPT) with total internal reflection fluorescence (TIRF) microscopy. We found that the mobility of individual enzymes was enhanced three-fold in the presence of the substrate, and the motion remained Brownian. We showed that the relative increase in diffusion is independent of the total enzyme concentrations; and the oligomerization state of enzymes did not change during the catalytic turnover. These experiments ruled out the possibility that the enhanced enzyme diffusion was caused by the …

Intrinsically Disordered Protein Regions In Human Evolution And As Therapeutic Targets, Karen Paco Mendivil

KGI Theses and Dissertations

Intrinsically disordered proteins (IDPs) and IDP regions (IDPRs) fail to form stable structures but have important biological functions via interacting with various molecular partners (proteins, DNA, RNA, glycosaminoglycans). We hypothesized that IDPRs are potential targets for therapeutics development because they are reservoirs of evolutionary innovation, and they play crucial roles in adaptation to pathogens.

We first studied the evolution of IDPRs in the human proteome and compared it with the proteome of non-human primates. We have found that evolutionary young protein-coding genes have included low conserved regions in the N-terminal part of proteins, and such regions are linked to high …

A Review Of Calcineurin Biophysics With Implications For Cardiac Physiology, Ryan B. Williams

Theses and Dissertations

Calmodulin is a prevalent calcium sensing protein found in all cells. Three genes exist for calmodulin and all three of these genes encode for the exact same protein sequence. Recently mutations in the amino acid sequence of calmodulin have been identified in living human patients. Thus far, patients harboring these mutations in the calmodulin sequence have only displayed an altered cardiac related phenotype. Calcineurin is involved in many key physiological processes and its activity is regulated by calcium and calmodulin. In order to assess whether or not calcineurin contributes to calmodulinopathy (a pathological state arising from dysfunctional calmodulin), a comprehensive …

Granulins In Norm And Neurodegenerative Pathologies, Anukool Bhopatkar

Dissertations

Granulins (GRNs) are small, cysteine-rich modules produced from the proteolytic cleavage of the precursor protein called progranulin (PGRN). GRNs are present in the form of seven tandem repeats within the precursor and are known to be produced in the extracellular and in lysosomal environments. In physiology, PGRN and GRNs plays pleiotropic roles such as neuronal growth and differentiation, immunomodulation, wound healing. Recent studies have implicated pathological role for PGRN in Alzheimer disease (AD) and frontotemporal dementia (FTD) but specific mechanism(s) remains unclear. However, potential interactions between GRNs and Ab42 and TDP-43 seem like a plausible underlying mechanism. Studies presented here …

Adrenocortical Attunement, Reactivity, And Potential Genetic Correlates Among Parent-Daughter Dyads From Low-Income Families, Jennifer Byrd-Craven, Michael M. Criss, Jessica L. Calvi, Lixian Cui, Amanda Baraldi, Amanda Sheffield Morris

Athletic Performance Research

Examining the multitude of influences on the development of adolescent stress responses, especially among low-income families, is a critical and understudied topic in the field. The current study examined cortisol attunement between adolescent girls and parents (mostly mothers) from predominantly low-income, single parent, ethnic minority families before and after an in-laboratory disagreement discussion task. The sample consisted of 118 adolescents (M_age = 13.79 years, 76.3% ethnic minorities, 23.7% European Americans) and primary caregivers (M_age = 40.62 years; Mdn yearly income = $24,000; 43.2% single parents; 50% living below poverty line). We investigated oxytocin receptor (OXTR rs53576) …

Utilizing Computational Approaches To Study Tubulin- Tubulin Electrostatic Interactions, Tolulope Ayodeji Ale

Open Access Theses & Dissertations

Microtubules play significant roles in transporting cargos within the cell, as well as the cell cycle. They are essentially the highway for the transportation of cell organelles. Understanding the interactions among microtubule components is crucial for the treatment of neurodegenerative diseases and cancer. In this study, we utilize a series of computational approaches to study the electrostatic interactions at the binding interfaces of interacting tubulin monomers. Our study revealed that the electrostatic attractive interactions in the αβ tubulin dimer is the strongest while the interaction between two αβ tubulin dimers in the longitude direction is the weakest. The result identified …

Engineering Fluorescently Labeled Human Fibroblast Growth Factor One Mutants And Characterizing Their Photophysics Properties Towards Designing Fret Assays, Mamello Mohale

Graduate Theses and Dissertations

Human fibroblast growth factor one (hFGF1) belongs to a family of 22 FGF members produced by fibroblast cells. Cell signaling during physiological processes of angiogenesis and wound healing occurs when hFGF1 binds to its receptor (FGFR). However, when heterogenous homeostasis is not maintained, fibroblast cells exhibit excessive proliferation which can lead to a myriad of cancers. smFRET is an ultrasensitive distant dependent (1-10 nm) technique capable of resolving such heterogeneity in structural dynamics and binding affinities (Kd). Therefore, we successfully designed and characterized fluorescently labeled hFGF1 tracers which span the visible light region of the electromagnetic spectrum for use in …

Deciphering Chemomechanical Couplings In Proteins Using Microsecond-Level Molecular Dynamics Simulations, Vivek Govind Kumar

Graduate Theses and Dissertations

All-atom molecular dynamics (MD) simulations combine the high temporal resolution of experimental methods like smFRET and spatial resolution of methods like x-ray crystallography, to provide a detailed dynamic picture of biomolecular processes. Here, microsecond-level atomistic MD simulations have been used to characterize chemomechanical couplings in human fibroblast growth factor 1 (hFGF1) and the spike proteins of SARS CoV-1 and SARS-CoV-2. hFGF1 is a globular signaling protein that is involved in several physiological processes ranging from cell proliferation to wound healing. Experimental studies have previously described the low proteolytic and thermal stability of hFGF1, in addition to the stabilizing role of …

Liposomes: Production And Applications For Controlled Drug Delivery, Gamid Abatchev

Boise State University Theses and Dissertations

This dissertation recognizes the enormous potential presented by the ever-evolving development of liposomes as drug carriers and seeks to offer further investigation into their useful production and utilization. The first chapter presents the basic principles governing their formation by self-assembly in water solutions, briefly describes the most common production methods, and points out essential past advances that led to their use as drug carriers. Chapter two exemplifies production of liposomes by the traditional methods of extrusion and sonication, detailing passive and active loading, as well as physical characterization by Dynamic Light Scattering, microscopy imaging, and fluorescence spectroscopy. In the next …

Structure Of A Monomeric Photosystem Ii Core Complex From A Cyanobacterium Acclimated To Far-Red Light Reveals The Functions Of Chlorophylls D And F, Christopher J. Gisriel, Gaozhong Shen, Ming-Yang Ho, Vasily Kurashov, David A. Flesher, Jimin Wang, William H. Armstrong, John H. Golbeck, Marilyn R. Gunner, David J. Vinyard, Richard J. Debus, Gary W. Brudvig, Donald A. Bryant

Publications and Research

Far-red light (FRL) photoacclimation in cyanobacteria provides a selective growth advantage for some terrestrial cyanobacteria by expanding the range of photosynthetically active radiation to include far-red/near-infrared light (700–800 nm). During this photoacclimation process, photosystem II (PSII), the water:plastoquinone photooxidoreductase involved in oxygenic photosynthesis, is modified. The resulting FRL-PSII is comprised of FRL-specific core subunits and binds chlorophyll (Chl) d and Chl f molecules in place of several of the Chl a molecules found when cells are grown in visible light. These new Chls effectively lower the energy canonically thought to define the “red limit” for light required to drive photochemical …

Mechanistic Insight Into Β-Lactamase Catalysis, Inhibitor Design And Resistance, Michael Trent Kemp

USF Tampa Graduate Theses and Dissertations

The emergence of antibiotic resistance and spread of Gram negative bacteria poses a very real health threat to the public. The main mode of resistance within Gram negative bacteria is the production of β-lactamase enzymes that catalyze the breakdown of β-lactam antibiotics through a hydrolysis mechanism. Once the β-lactam ring is hydrolyzed and opened, the drug loses its efficacy, which allows for the bacteria to grow and proliferate uninhibited. These β-lactamase enzymes are organized into four categories based on the Ambler classification, with classes A, C and D being denoted as serine-based β-lactamase enzymes. Class B is composed of metalloenzymes …

Investigation Of Immobilized Enzymes In Confined Environment Of Mesoporous Host Matrices, Xiaoliang Wang

USF Tampa Graduate Theses and Dissertations

Enzyme immobilization in metal-organic frameworks (MOFs) as a promising strategy, is attracting the interest of scientists from different disciplines with the expansion of MOF’s development. Different from other traditional host materials, their unique strengths of high surface areas, large yet adjustable pore sizes, functionalizable pore walls, and diverse architectures make MOFs an ideal platform to investigate hosted enzymes, which is critical to the industrial and commercial process. In addition to the protective function of MOFs, the extensive roles of MOFs in the enzyme immobilization are being well-explored by making full use of their remarkable properties like well-defined structure, high porosity, …

A Nosy Neighbor: Purification And Functional Characterization Of Lpg2149, Ashley M. Holahan

The Journal of Purdue Undergraduate Research

Ubiquitination is a process that marks proteins for various cell-signaling pathways, namely protein degradation and other processes. Th ese pathways are essential in a wide array of cellular processes, including defense mechanisms against invading pathogens. Th e ubiquitination process is universally found in all eukaryotic organisms, including plants and animals, and thus plays a vital role in cellular homeostasis. Recently, more discoveries have been made on prokaryotic effector proteins that hijack the ubiquitination system even when they do not possess a ubiquitin system of their own. MavC, also known as lpg2147 (Gan, Nakayasu, Hollenbeck, & Luo, 2019; Puvar et al., …

Determining The Primary Dna Substrates Of Shld2'S Ob-Fold Domains, Hari Patchigolla

Holster Scholar Projects

Failure to repair DNA double-stranded breaks leads to cell death. Radiation therapy is commonly used to kill cancer cells by inducing these breaks. However resistance to radiation therapy, due to a hyperactive DNA double-stranded break repair pathway, is a common occurrence that makes cancer patients more prone to relapse. The Shieldin complex is shown to promote DNA-double stranded break repair by binding to DNA at sites of damage. Thus, the objective of this project is to understand the affinity and type of DNA that Shieldin binds to, through gel-shift assays, for the eventual creation of an inhibitor for this protein …

Loren Haarsma - When Did Sin Begin?, Loren Haarsma

University Faculty Publications and Creative Works

Patrick Hamilton speaks to Calvin University Professor, Loren Haarsma, about the origins of sin and various ways to make sense of the doctrine of original sin in light of evolutionary origins. Other topics of conversation include psychology, free will and the theology of Saint Augustine.