Biochemistry Commons^™

Sec-Saxs And Sans Analyses Of The Talin•Vinculin Complex, Gilbert Reyes

Dissertations, Theses, and Capstone Projects

Focal adhesions (FA) are integrin-based cell-matrix adhesion sites composed of adaptor proteins that facilitate the generation of traction forces important for biological functions such as cell migration, embryo development, wound healing, tissue organization and stability, and immune responses. Mature FA are observed when both autoinhibited multi-domain scaffolding protein talin and membrane-cytoskeletal protein vinculin are activated and interact thus promoting the assembly and function of FA. While research has resolved truncated sections of autoinhibited talin and recruitment of vinculin due to mechanotransduction that exposes cryptic vinculin binding sites (VBS), little is known about the global modifications of full length talin in …

Investigating Quinclorac Binding To Human Serum Albumin Using Spectroscopy And Molecular Docking, Le Nguyen, L. Hicks, L. Jodoin, S. Carby, D. S. Sanford, D. Benavides, A. Mishra, R. Yadav

Journal of the Arkansas Academy of Science

Human serum albumin (HSA) is the most abundant plasma protein and serves as a major transporter and reservoir for a wide range of endogenous ligands, including fatty acids, heme, bilirubin, prostaglandins, and metal ions, as well as numerous exogenous compounds, such as pharmaceuticals. HSA is a 66 kDa monomeric, multidomain protein containing two principal ligand-binding sites, Sudlow sites I and II. Sudlow site I contains Trp214, the sole tryptophan residue in HSA, whose intrinsic fluorescence provides a sensitive probe for studying ligand–protein interactions.

In this study, the interaction between HSA and the persistent organochlorine herbicide quinclorac (QNC) was investigated using …

Microtubules In Breast Cancer: Exploring The Α/Β-Tubulin Toggle Switch And Its Implications In Human Breast Cancer, Annemarie Ianos

Student Theses and Dissertations

Microtubules, composed of a/b-tubulin heterodimers, play a central role in breast cancer tumor growth by polymerizing, leading to metastasis and depolymerizing, contributing to proliferation. Human enzymes protein kinase Ca (PKC-a) and cyclin-dependent kinase 1 (Cdk-1) mediate phosphorylation at sites a:Ser165 and b:Ser172, respectively, influencing the growth of microtubules. It is possible that alternating phosphorylation at these sites contribute to an a/b-tubulin “toggle switch” that mediates microtubule instability and tumor growth.

The project investigates the influence of the toggle switch model on microtubule stability by determining the impact of mutants (a:S165D, a:S165N, a:S165S_P, b:S172S_P and a:S165S_P/b:S172S …

Understanding Tlr3 Immune Response Activation In Cryptosporidium Parvum And Cryspovirus Pathogenesis, Surayya Hudayberganova

Biochemistry and Molecular Biology

Cryptosporidiosis is a serious gastrointestinal illness caused by a protozoan parasite known as Cryptosporidium. It is particularly dangerous for malnourished children and those with compromised immune systems. My research focuses on the Toll-like receptor 3 (TLR3) response to the Cryptosporidium parvum infection, specifically in the presence of the parasite’s viral mutualist named cryspovirus (CSpV1). Results using research methodologies like ELISA and RT-qPCR have indicated that TLR3 expression increases during the infection process of Cryptosporidium parvum (C. parvum). Furthermore, one intriguing observation concluded during this study suggests that administering the TLR3-specific inhibitor CU-CPT4a to infected cells drastically decreased this activation. This …

Understanding The Role Of Toxs As A Bile Sensing Component Of The Toxrs Virulence Regulatory System In Vibrio Spp., Minje Kim

Dartmouth College Ph.D Dissertations

Pathogenic Vibrio bacteria, such as V. cholerae and V. parahaemolyticus, colonize in the human small intestine to cause severe gastrointestinal disease. During the infection, these bacteria encounter bile salts, antimicrobial cholesterol metabolites secreted into the intestine. Pathogenic Vibrio species have evolved to utilize bile salts as signals to regulate virulence. The signaling depends in part on ToxRS, a conserved co-component transmembrane transcription regulator. ToxRS consists of the transcription factor ToxR and its membrane-tethered binding partner ToxS. ToxS is required for ToxR stability and full transcriptional activity. Although bile salts are known to influence ToxRS-dependent virulence gene expression, the molecular …

G-Quadruplex Dna-Driven Genomic Instability Under Ber Loss, Addison Belick, Claryssa Gutierrez, Joslynn Rosas, Andrea Vargas

Posters - 2026

Base Excision Repair (BER) is a cellular tool that can repair damaged DNA (Hindi et al., 2022, Cellular and Molecular Life Sciences). G-quadruplexes (G4s) are unique 4-stranded structures in DNA or RNA that are rich in guanine (Gray et al., 2023, Nat. Chem. Biol). The purpose of this study is to understand whether BER contributes to the removal of G4s in DNA. This will determine if the BER-deficient yeast is more sensitive to treatment with G4-binding drugs than the BER-proficient yeast. We will replace the APN1 gene in the yeast genome with the URA3 gene, because the wild type yeast …

Dna Stability In Aqueous Solutions: A Case Study On Poly A - Poly T Duplex Using Molecular Dynamics Simulations, Haripriya Chennuru

Biochemistry and Molecular Biology

This thesis relies on molecular dynamics (MD) simulations, which apply the AMBER software package to analyze the structural stability, energetics, and dynamics of Poly A - Poly T DNA duplexes. This work is mainly concerned with testing configurations of non-bonded interaction cutoffs (12 Å and 15 Å) on the Generalized Born solvation models (IGB1 and IGB2) to determine the most appropriate conditions regarding computation time and physical reliability in DNA molecular dynamics. The solvation models enable effective simulation of solvent effects, facilitating the calculation of simulation parameters to evaluate structural stability within different environmental conditions. Overall, the performance indicates that …

4e-Bp1 Differentially Regulates Translation Of A Subset Of Human Mrnas, Mehreen Mahbub

Dissertations, Theses, and Capstone Projects

Elevated levels of eukaryotic initiation factor 4E-binding protein 1 (4E-BP1) influence cap-independent translation by forming a complex with eukaryotic initiation factor 4E (eIF4E) (eIF4E•4E-BP1). Certain mRNAs—including those encoding hypoxia-inducible factor-1α (HIF-1α), fibroblast growth factor-9 (FGF-9), and two isoforms of tumor suppressors, p53 (p53_A, and p53_B)—contain structured 5’untranslated regions (UTRs) that enable translation either via cap-independent translation enhancer (CITE)-like or internal ribosomal entry site (IRES)-like mechanisms. However, how 4E-BP1 modulates these mechanisms remains unclear. Using fluorescence-based anisotropy assays, we showed that the eIF4E•4E-BP1 binds more tightly to the 5’ m⁷G-cap of these mRNAs than eIF4E …

Protein Allostery Probed By Ligands Across Sites, Virgil A. Woods

Dissertations, Theses, and Capstone Projects

Allostery is a pervasive regulatory principle throughout biology, yet the structural pathways by which distal inputs alter active‑site chemistry within protein structures remain incompletely defined and exploited. This dissertation uses protein tyrosine phosphatase 1B (PTP1B) as a tractable model to map those pathways with complementary experimental and computational tools. I integrate high‑resolution hydrogen-deuterium exchange mass spectrometry (HDX-MS), room-temperature crystallography, NMR, steady-state kinetics, crystallographic pseudo-ensembles, and machine-learning-guided ligand discovery. The working premise is that regulation reflects redistribution within a conformational ensemble rather than a binary switch. That orthogonal perturbations by small molecules, mutations, and protein partners can be used to both …

Structural Characterization Of Peptide Nanoaggregates At Varying Concentrations And Their Impact On Cellular Responses, Malika Rozmetova

Theses and Dissertations

Peptide nano-assemblies can regulate cellular pathways in a structure-dependent manner. Here, we show that the enzyme-responsive peptide NapFFK(NBD)Yp forms distinct nanoscale assemblies at different concentrations, triggering differential ER stress and extracellular vesicle release in MDA-MB231 cells. These results highlight the importance of supramolecular organization in peptide–cell interactions.

Seeing Through The Fuzz: Understanding Conformational Diversity In The Fuzzy Coat Of Amyloids Across Fibril Polymorphs Using Solid-State Nmr, Carah K. Allen

Scripps Senior Theses

The aggregation of α-synuclein (α-syn) into amyloid fibrils is a central pathological hallmark of Parkinson’s disease and other related synucleinopathies. Although monomeric α-syn is intrinsically disordered, the protein assembles into multiple fibril polymorphs that differ in their β-sheet core structures. Surrounding each polymorph is the “fuzzy coat,” which is a highly dynamic, intrinsically disordered region (IDR) that is not resolved by high-resolution structural techniques, such as Cryo-EM, but is thought to influence fibril interactions, propagation, and toxicity. Understanding whether different polymorphs maintain distinct fuzzy-coat conformational ensembles is therefore essential for connecting amyloid structure to biological function. To address this question, …

Channel-Opening Kinetics Of Complex Kainate Receptors, Noah S. Saunders

Electronic Theses & Dissertations (2024 - present)

Ionotropic glutamate receptors (iGluRs) are found both pre- and postsynaptically in neuronal membranes, and mediate the majority of fast excitatory synaptic transmission in response to the binding of glutamate, a major excitatory neurotransmitter in the central nervous system (CNS). Ionotropic glutamate receptors are divided into three distinct subtypes: kainate, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), and N-methyl-D-aspartic acid (NMDA) receptors. Auxiliary proteins specific to each receptor subtype also play a role in tuning both receptor expression and gating properties, such as neuropilin and tolloid-like (NETO) proteins that modulate kainate receptors, and transmembrane AMPA receptor regulatory proteins (TARPs) that regulate AMPA receptors. Like …

Photo And Spatial Control Of Rna Structures And Functions: Exploring Positional Effects And Photo-Responsiveness Of Azobenzene Modified Nucleotides, Jinxi Du

Electronic Theses & Dissertations (2024 - present)

RNA molecules perform many important biological functions by forming complex three-dimensional structures stabilized by base pairing, tertiary interactions, and metal ion coordination. Because RNA function depends strongly on its structure, methods that allow reversible control of RNA conformation and activity are important for understanding RNA behavior and for potential therapeutic applications. However, achieving reversible and site-specific control of RNA structure, especially at the single-nucleotide level, remains challenging. In this dissertation, I developed and applied azobenzene-modified nucleotides as a chemical tool to enable optical and spatial control of RNA structure and function.

The first part of this dissertation focuses on establishing …

Evaluating Bmx-001 As A Selective Radioprotector For Healthy Tissue In Pelvic Cancers, Molly Myers

Theses & Dissertations

Pelvic cancers, including rectal, anal, and prostate cancer, are relatively survivable cancers with high five-year survival rates, partially due to the addition of radiation to treatment regimens. Radiation confers excellent tumor control, but also causes damage to surrounding tissue, resulting in both short-term and long-term side effects. In a patient population that is surviving longer after treatment, limiting the impact of side effects is instrumental to improving patient quality of life. Radiation-induced ROS is instrumental in causing these side effects and provides a unique opportunity to protect healthy tissue from damage while sensitizing cancer tissue to treatment, as cancer cells …

Structural Basis Of A Class Ii Ribonucleotide Reductase Found If Mycobacterium Tuberculosis, Leah Jacob

Student Scholar Symposium

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains a leading global health challenge, particularly due to its ability to enter a dormant, drug-tolerant state that enables long-term persistence within the host. Just before dormancy, Mtb replicates its entire genome creating DNA precursors for when the infection reactivates. Ribonucleotide reductases (RNRs) play a critical role in bacterial survival by catalyzing the conversion of ribonucleotides into deoxyribonucleotides, a necessary step for DNA replication and repair. The class II RNR, NrdZ, has been implicated in facilitating Mtb persistence under hypoxic stress conditions, yet its structural and mechanistic function remains largely uncharacterized. …

From Sequence To Allostery: How Amino Acid Differences Rewire Coupled Conformational Heterogeneity In The Ptp Enzyme Family, Shivani Sharma

Dissertations, Theses, and Capstone Projects

Protein Tyrosine Phosphatases (PTPs) are critical regulators of cellular signaling, and their activity is often modulated through allosteric mechanisms. Allostery is defined as a chemical or conformational change in one site of the protein due to a binding event at another site. Although several studies have investigated aspects of allostery in PTPs, the mechanistic foundations underlying allosteric regulation remain poorly understood. Despite a highly conserved catalytic domain across PTPs, regions with low or no conservation suggest potential "rewiring" of allosteric networks. This raises key questions about the universality versus individuality of allosteric mechanisms across the PTP family.

In this work, …

Advancing Single-Molecule Nanopore Sensing: From Protein Conformation And Metal Binding To Dna Transport Via Hybrid Nanostructures, Matthew J. Odonohue

Multidisciplinary Studies Theses and Dissertations

This dissertation presents the development and application of solid-state and hybrid nanopore platforms for single-molecule analysis of biomolecular interactions. First, a silicon nitride nanopore was employed to characterize the conformational states of the transferrin receptor (TfR), enabling discrimination between its monomeric and dimeric forms, as well as from its ligand, human serum transferrin (hSTf), despite their similar molecular weights. In a separate study, the same nanopore configuration was used to track the real-time binding of titanium ions to transferrin, demonstrating single-molecule sensitivity to metal-induced conformational changes. A hybrid microtubule–solid-state nanopore (MT–SSN) was then engineered, repurposing microtubules as electrostatically anchored conduits …

Advanced Interactions Of Directed Energy With Retinal Pigment Epithelial Cells And Their Photochemical And Photothermal Responses, Jin B. Ha

Theses & Dissertations

Excess optical radiation can injure the retina through either rapid heat deposition (photothermal damage) or cumulative photo‑oxidative stress (photochemical damage), yet current laser‑safety limits treat these mechanisms as independent. To test that assumption, this dissertation integrated systematic wavelength, duration and temperature‑controlled laser exposures with live/dead fluorescence imaging in a melanin‑loaded hTERT‑RPE1 monolayer model. First, concurrent 447 nm (blue) and 2 µm (infra‑red) beams delivered for 200 s demonstrated a strong thermal–photochemical synergy: each beam alone was sub‑threshold (≤25 % lethality) but together produced 100 % RPE death without exceeding 50 °C, proving that modest heating markedly lowers the photon dose …

Elucidating The Roles Of Eukaryotic Initiation Factors Involved In Dap5 Mediated Translation, Jacob Nk Quartey

Dissertations, Theses, and Capstone Projects

Translation initiation in eukaryotes is a highly regulated process essential for accurate protein synthesis. It is a dynamic process that involves a complex interplay between messenger RNAs (mRNAs), ribosomal subunits, and a host of initiation factors, ensuring precise start codon selection and the subsequent assembly of the translation machinery. This process has well been known to be mediated by the eukaryotic Initiation Factor (eIF4F), which consists of the cap binding protein eIF4E, the scaffolding protein eIF4GI, and the helicase factor eIF4A.The recognition and binding of eIF4E to the m⁷G cap structure of the mRNA is essential for the …

Biophysical Analysis Of S100a12 And The Nucleosome Core Particle, Christopher Diforte Jr.

Dissertations, Theses, and Capstone Projects

Calcium signaling and chromatin remodeling are fundamental regulatory processes that control protein activity and gene expression, respectively. This thesis investigates the molecular mechanisms by which local ligand binding and structural perturbations propagate allosteric effects across larger protein systems, using two distinct yet mechanistically analogous models: the calcium binding protein S100A12 and the nucleosome core particle. These studies are unified by a shared emphasis on how physical forces govern biological function.

In the first part, we explore calcium mediated allostery in S100A12, focusing on the distinct roles of its two EF-hand calcium binding loops (EF-I and EF-II). Through a combination of …

Characterization Of Sars-Cov-2 Replication And Transcription Complexes Via Structural And Evolutionary Approaches, Amelie Ghirardo, Ben Shabatian, Avishai Aghelian, Kyle Tau, Eleonora Gianti

Undergraduate Research

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused around 700M cases and over 7M COVID-19-related deaths recorded worldwide (World Health Organization, March 2025). Aiming to effectively combat this and other disease-causing Coronaviruses (CoV), unprecedented research efforts led to the development of new vaccines and antiviral therapies. Due to emergence of variants of concern (VOCs) with increased transmissibility, immune evasion from vaccination, and potential to resist the available treatments, SARS-CoV-2 continues to represent a major threat to global health. Hence, there is a pressing need to discover new antivirals with broad-spectrum efficacy against multiple SARS-CoV-2 variants and related CoVs. This project …

The Fractography Of Bone: Impact Of Flat Bone And The Story It Tells, Abigail Hoffmeister, Chase Freeman, Brandon Mendoza, Nathaniel Fitch, Annie Markarian, Jack Tran, Joshua Lau, Nicholas Tran

Seaver College Research And Scholarly Achievement Symposium

Fractography as a method for fracture analysis has been applied widely to materials that range from glass to ceramics and polymers of varying compositions. Very limited research has been done, however, to apply this knowledge of fractography and fracture patterns to bone. With the goal of telling the story of how a bone was broken, this research focuses on observing known patterns of fracture in polymers, and applying these patterns to bone. For the purposes of this research, porcine scapulae were acquired, dissected from surrounding tissue, and broken using a standardized weight drop at varying heights. The fractured bone was …

Host P53 Expression During C. Parvum Infection…Does The Virus Play A Role?, Jasdeep Kaur Dhanoa

Biochemistry and Molecular Biology

C. parvum infection induces significant host cellular stress responses, particularly through the modulation of p53 expression underscoring its potential involvement in gastrointestinal malignancies. Understanding these mechanisms is crucial for developing targeted therapeutic interventions. This study investigated the effects of C. parvum infection on host p53 dynamics in HCT-8 cells and assessed the impact of antiviral agents Lamivudine and Amantadine on the virus CSpV1 present within the parasite C. parvum. Further, the study focuses on whether the p53 effect changes with the presence or absence of CSpV1. The p53 assay results showed a constant increase in p53 activity after infection of …

Overexpression And Biophysical And Functional Characterization Of A Recombinant Fgf21, Phuc Phan, Jason Hoang, Thallapuranam Krishnaswamy Suresh Kumar

Chemistry & Biochemistry Faculty Publications and Presentations

Fibroblast growth factor 21 (FGF21) is an endocrine FGF that plays a vital role in regulating essential metabolic pathways. FGF21 increases glucose uptake by cells, promotes fatty acid oxidation, reduces blood glucose levels, and alleviates metabolic diseases. However, detailed studies on its stability and biophysical characteristics have not been reported. Herein, we present the overexpression, biophysical characterization, and metabolic activity of a soluble recombinant FGF21 (rFGF21). The far-UV circular dichroism spectra of rFGF21 show a negative trough at 215 nm, indicating that the protein’s backbone predominantly adopts a β sheet conformation. rFGF21 shows intrinsic tyrosine fluorescence at 305 nm. Thermal …

Probing The Stability Of Designed Protein, Axel Irianni, Shuvo Chakraborty, Maral Afshinpour

SDSU Data Science Symposium

Naturally occurring proteins have evolved to perform specific biochemical functions, and their amino acid sequences are optimized for those functions rather than for stability. Enhancing protein stability without compromising its function is highly desirable for biotechnological applications, such as vaccine design. Computational protein design algorithms offer a solution by making targeted amino acid changes to the native protein sequence, potentially enhancing stability without the need for the lengthy, labor-intensive, and costly experimental processes typically involved in stabilizing proteins. There are various categories of computational protein design algorithms, and it remains unclear which approach is the most effective. In this study, …

Ivy Proteins As Guardians Of Bacterial Cell Wall Integrity: Regulation Of Lytic Transglycosylases Explored, Aamna Aijaz, Trinity E. Alamutu, Vy T. Dao, Nathaniel R. Davis, Michael D. Landers, Nykolas K. Mackevicius, Liliana Ortiz, Irina F. Padilla-Montoya, Kacy J. Smith, Maria L. Snyder, Anthony J. Stefanie, Blaise M. Williams, Thomas C. Leeper

The Kennesaw Journal of Undergraduate Research

Lytic transglycosylases (LTs) are bacterial enzymes involved in biosynthesis and maintenance of the peptidoglycan cell wall. LTs are reported to be regulated by two paralogs of Inhibitor of Vertebrate Lysozymes: Ivyp1 and Ivyp2. This study investigated the regulatory dynamics between the soluble LT (SltB1), and Ivy paralogs as putative regulators in Pseudomonas aeruginosa (PA). The secondary objective was to delineate the critical roles played by a glutamic acid at position 135 in SltB1 and a histidine at position 62 in Ivyp1 in governing their molecular interaction through site directed mutagenesis. Isolated SltB1 shows no lytic activity in our assay, in …

The Role Of Secondary And Tertiary Structure In The Cap-Independent Translation Of Fgf-9 And Hif-1-Alpha, Amanda Michelle Whittaker

Dissertations, Theses, and Capstone Projects

Under normoxic conditions, eukaryotes initiate translation of RNA through eIF4E recognition of the 5’ cap. However, under cellular stress, eukaryotic translation must be initiated through a 4E-independent, or “cap-independent” mechanism, involving eukaryotic initiation factor 4G (eIF4G) binding directly to the 5’ untranslated regions (5’ UTR) of the RNA. eIF4G binding then recruits the ribosome to the transcript. While this mechanism is useful for translation of apoptotic transcripts and transcripts involved in cell survival, cap-independent translation is also utilized by oncogenic RNA for tumorigenesis. Previous work by our lab and others has categorized this recruitment and initiation mechanism as either internal-ribosome-entry-site …

Protein-Metal Interactions Of A-Synuclein And Bioactive Transition Metals Via Molecular Dynamics, Gonzalo R. Vazquez

Theses and Dissertations

Parkinson’s Disease (PD) is a neurodegenerative movement disorder which has been found to target the dopaminergic neurons of the substantia nigra. It is characterized by the formation of masses known as Lewy Bodies, formed by aggregates of the intrinsically disordered protein (IDP) -synuclein (asyn). Research suggests that alpha synuclein can undergo aggregation in the presence of heavy metals, which may accumulate in the body through a variety of mechanisms. To study how metals may play a role in wildtype (WT) asyn aggregation, MD simulation of the protein was performed in the presence of bioactive transition metals including Fe2+, Fe3+, Cu+, …

Redox Control In A Fused Electron Transfer Flavoprotein From A Thermophilic Archaeon And Expanded Significance Of A Hydrogen Bond From A Conserved Histidine Residue That Contributes To Flavin Redox Tuning And Activation For Covalent Modification, Debarati Das

Theses and Dissertations--Chemistry

In absence of O₂ as terminal electron acceptors in anaerobic bacteria and archaea, carbohydrate metabolism is 15 times less efficient compared to aerobic energy metabolism resulting in energy deficit conditions. Despite their meager resources these anaerobes were able to generate H₂ and a chemiosmotic potential able to drive energy demanding reactions such as CO₂ or N₂ fixation. These observations raised concerns as production of high energy reductants (H₂) from mediocre fuels (NADH) defied the laws of thermodynamics.

In 2008, a known mechanism “electron bifurcation” but with flavins as redox mediators instead of quinones was …

Impact Of Membrane Lipid Composition On The Structure And Function Of Uncoupling Proteins 1 And 2 From Arabidopsis Thaliana (Atucp1 And Atucp2), Elizabeth Silva

Theses and Dissertations (Comprehensive)

A proton gradient across the inner mitochondrial membrane (IMM) is required for the synthesis of adenosine triphosphate (ATP) via ATP synthase. In other words, generation of the proton gradient is coupled to the synthesis of ATP. Interestingly, uncoupling proteins (UCPs), also located in the IMM, dissipate the proton gradient, meaning that the gradient is not efficiently used for the production of ATP.¹ The mechanism of proton transport activity of UCPs has been hypothesized and widely debated for the past 20 years to also reduce oxidative stress by reducing the production of reactive oxygen species (ROS).² The majority of …