Computational Chemistry Commons^™

Computational Insights Into Nucleosome Dynamics In Epigenetics Using Molecular Dynamics Simulations, Rutika Patel

Dissertations, Theses, and Capstone Projects

Nucleosome core particles (NCP) are the building blocks that form a highly organized and compact chromatin structure. Nucleosomes package DNA in the nucleus of eukaryotic cells. The NCP consists of about 147 base pairs of DNA wrapped around the histone octamer, with 1.65 superhelical turns in a left-handed manner. The histone octamer is composed of two copies of H3, H4, H2A, and H2B. Together with histone H1 and linker DNA, they further assemble into a higher-order chromatin structure. The nucleosome complex is stabilized by electrostatic interactions between positively charged histone residues and the negatively charged DNA backbone. To effectively access …

Supramolecular Assembly In Short Peptide Systems For Selective Metabolite Recognition And Drug Nanoencapsulation, Maithreyi Ramakrishnan

Dissertations, Theses, and Capstone Projects

Short peptides can form adaptive supramolecular assemblies, and understanding how minimal sequences organize around neurometabolites or hydrophobic cancer drugs enables the rational design of functional materials. This thesis combines molecular dynamics with experimental validation to establish design rules linking peptide sequence to emergent structure and function. Chapter 1 outlines the molecular determinants governing peptide assembly. Chapter 2 reviews computational workflows that reveal sequence-dependent conformations and supramolecular organization. Chapter 3 applies these principles to Dynamic Peptide Libraries which identify tetrapeptides that selectively interact with neurometabolites. Chapter 4 extends the same interaction-driven framework to design tryptophan-rich pentapeptides that co-assemble with kinase inhibitors …

The Role Of Water In Peptide Behavior And Peptide-Based Water-Responsive Crystals, Janel Jannette Rivera Cancel

Dissertations, Theses, and Capstone Projects

Water plays a crucial role in shaping the behavior and function of biomolecules across the liquid, supercooled, and glassy states. This thesis presents a dual approach combining computational simulations and experimental investigations to explore the influence of water on biomolecular systems, particularly peptide-based materials. We employ molecular dynamics simulations to study the hydration-dependent structural dynamics of homopolymer peptides. Simulations were carried out across a range of temperatures and pressures to analyze changes in hydration and structural stability, shedding light on the behavior of peptides under supercooled and glassy conditions. These studies are especially relevant for understanding biomolecular stability in cryopreservation. …

Characterizing Electrospray Performance Of Hydroxylammonium Nitrate (Han) And 2-Hydroxyethylhydrazinium Nitrate (Hehn) Ionic Liquids By Mass Spectrometry And Dynamics Simulations, Wenjing Zhou

Dissertations, Theses, and Capstone Projects

Dual-mode propulsion combines chemical and electric propulsion methods into a single compact system by sharing hardware and propellant for both modes, offering complementary advantages tailored to specific mission needs. A promising propellant candidate for dual-mode propulsion is a binary mixture of hydroxylammonium nitrate (HAN) and 2-hydroxyethylhydrazinium nitrate (HEHN) ionic liquids (ILs). Each of the two ILs was developed as a greener alternative to the traditional, yet toxic, hydrazine monopropellant used in chemical propulsion. Recently, their potentials in electrospray propulsion have garnered attention. This thesis focused on the investigation of reaction dynamics and kinetics of HAN, HEHN and their binary mixture …

Consequences Of Oxidative Dna Damage: Base-Pair Dissociation, Singlet Oxygenation And Dna-Protein Crosslinking, May Myat Moe

Dissertations, Theses, and Capstone Projects

8-Oxo-2′-deoxyguanosine (OG) is a common DNA lesion resulting from oxidatively generated damage and pairs with complementary cytidine (C) in Watson Crick base-pairing within duplex DNA. The WC-OG·C lesion, if not recognized or repaired, not only leads to G⋅C→T⋅A transversion mutations (through Hoogsteen (HG) base pairing of OG⋅A), but also renders the base pair being more vlunerable to ionizing radiation and singlet oxygen (1O2) damage. Leveraging on our previous accomplishments on the study of gas-phase reactions of 1O2 with 2′-deoxyguanosine radical cations, my research thesis expanded to the investigation of reaction dynamics of 9-methyl-8-oxoguanine (9MOG) radical cations. The experiments of following …

Investigating Dna Damage Caused By Reactive Oxygen And Nitrogen Species Via Guided-Ion-Beam Scattering And Computational Techniques, Jonathan Benny

Dissertations, Theses, and Capstone Projects

Among DNA nucleobases, guanine (G) is the primary target for one-electron ionization and oxidation, generating G●+ through various processes, including photooxidation, electrocatalytic oxidation, DNA-binding transition metals, ionizing radiation, and photolysis. This is due to the low adiabatic ionization potential and oxidation potential of guanine. Electron holes from other nucleobases can move to guanine, proving that G●+ production traps oxidative DNA damage. G●+ formation can exacerbate DNA damages and cause secondary reactions from reactive oxygen species (ROS) and reactive nitrogen species (RNS) during pathological processes. The following three projects were conducted using a customized electrospray ionization (ESI) guided-ion-beam tandem mass spectrometer, …

Studies On The Synthesis, Function, And Properties Of Troponoids, John-Charles A. Baucom

Dissertations, Theses, and Capstone Projects

Troponoids are a unique class of non-benzenoid aromatic compounds with a wide range of demonstrated applications in pharmaceuticals and molecular sensing. The cycloheptatrienone scaffold possesses a noteworthy degree of tunability as a function of ring oxygenation. This manuscript describes our efforts toward a better understanding of the physical consequences of the scaffold to better utilize the motif. Chapter the first discusses our efforts at elucidating the mechanism of troponoid inhibition of the Hepatitis B virus reverse transcriptase RNAse H enzymatic domain. Using homology modeling in conjunction with traditional in vitro assays we were able to establish the likely mechanism of …

Solvation Thermodynamic Mapping Approaches For Computer-Aided Drug Discovery, Vjay Molino

Dissertations, Theses, and Capstone Projects

The drug discovery process is inherently long and costly, prompting the development and integration of computational tools to mitigate these challenges. One of area explored in computer-aided drug discovery is to understand the role of solvation in protein-drug binding and to develop computational tools and methods that can be integrated in the drug discovery process. Grid Inhomogeneous Solvation Theory (GIST) is a tool that provides a framework for mapping solvation thermodynamiproperties of water molecules on the protein surface.This thesis explores the use of GIST in generating pharmacophore models and elucidates the role of solvation in protein structural fluctuations.

One of …

Novel Alchemical Methodologies For Modeling Molecular Binding, Solmaz Azimi

Dissertations, Theses, and Capstone Projects

Molecular recognition is fundamental to all biological and biochemical processes. Understanding the interactions between molecules is the foundation for drug discovery and development, for understanding biological processes, and for the design of biosensors and nanomaterials. There is tremendous interest in the development of computer models to predict molecular association equilibria. In structure-based drug discovery enterprises, predicting the strength and selectivity of a small molecule to a biological target can advance target identification, aid ligand design, and accelerate high-throughput screening of drug compounds. This work focuses on free energy models, a class of computational methodologies grounded on the fundamental physical and …

The Role Of Confined Hydration And Water Reorganization In Molecular Binding, Joe Z. Wu

Dissertations, Theses, and Capstone Projects

An important factor in guiding the development of drug discovery efforts is the comprehensive assessment of a ligand or drug’s ability to bind its receptor. The metric used to measure this interaction strength is by calculating the binding free energy (BFE). To achieve this accurately, we combine two concepts: (1) Grid Inhomogeneous Solvation Theory (GIST) returns the local water thermodynamic and structural contributions to free energy; and the (2) Alchemical Transfer Method (ATM) obtains the absolute (ABFE) and relative binding free energy (RBFE) estimates between ligand pairs. In this work, we employ Alchemical Water-Transfer to tether bridging water(s) during the …

Incorporating Solvation Thermodynamic Mapping In Computer-Aided Drug Design, Yeonji Ji

Dissertations, Theses, and Capstone Projects

Advancements in computational techniques have revolutionized structure-based drug design, substantially improving the efficiency and effectiveness of the drug discovery process by reducing time, costs, and labor requirements. These advancements include various methods, such as investigating small molecule ligands binding to proteins, exploring alternative protein conformations, and solvation mapping on the protein surfaces. Among these methods, understanding the correlation between protein-ligand binding and the role of solvation is important.

A fundamental concept in protein-ligand binding is shape and electrostatic complementarity, which is complicated by the inherent flexibility of proteins. In the absence of small molecule ligands, proteins are complementary to surface …

Protein And Water Modeling In Computer-Aided Drug Discovery, Mossa Ghattas

Dissertations, Theses, and Capstone Projects

The field of Computer-Aided Drug Design (CADD) is continuously evolving to improve protein modeling, a crucial step in the drug discovery process. However, limitations exist in how CADD accounts for the various configurations a protein can adopt due to different rotamer and protonation states of its residues. This thesis explores advancements in CADD to address this challenge, focusing on protein modeling and water interactions.

In Chapter 1, I introduce the drug discovery process with a brief overview of its history, the purpose of FDA clinical trials, and the cost and time duration for bringing a drug to the market. I …

Development Of Platinum(Iv)-Gold(I)-Based Anticancer Agents, Javier E. Lopez-Hernandez

Dissertations, Theses, and Capstone Projects

Heterometallic compounds have emerged as prospective multitarget anticancer drugs. These species may display improved efficacy and physicochemical properties compared to the individual metallic fragments, while helping combat drug resistance by exerting effects on multiple pathways. In this thesis we describe the synthesis of new bi- and tri-metallic compounds based on platinum(IV) compounds containing FDA-approved platinum agents, and gold(I) derivatives with known anticancer properties. We demonstrate their toxicity and selectivity against a small panel of renal, bladder, ovarian, and breast cancer cell lines, as well as their synergistic effects. We have selected a trinuclear PtAu₂compound containing the Pt(IV) core …

Mechanistic, Biochemical, And Theoretical Studies Of Phototoxicity And Photobluing, Lloyd M. Lapoot

Dissertations, Theses, and Capstone Projects

This thesis consists of four chapters as detailed below:

Chapter 1 discusses the photoconversion of heptamethine to pentamethine cyanines and of pentamethine to trimethine cyanines. Here, we report mechanistic studies and initial experimental evidence for a previously unexplored 4-carbon truncation reaction that converts the simplest heptamethine cyanine to the corresponding trimethine cyanine. We propose a DFT-supported model describing a singlet oxygen (¹O₂) mediated formation of an allene hydroperoxide intermediate and subsequent 4-carbon loss through a retro-Diels-Alder process. Fluorescence and mass spectrometry measurements provide evidence for this direct conversion process. This 4-carbon truncation reaction adds to growing …

Development And Application Of Magnus Expansion Based Propagators For Problems In Spectroscopy And Quantum Dynamics, Taner M. Ture

Dissertations, Theses, and Capstone Projects

Stable and accurate numerical propagators of time-evolution equations in quantum mechanics are required to capture correct dynamical behavior, especially in the long time limit. Magnus expansion (ME) provides a general way to expand the real time propagator of a time dependent Hamiltonian within the exponential such that the unitarity is satisfied at any order. Integrators are developed by truncating the ME and using explicit integration of Lagrange interpolation formulas for the time dependent Hamiltonian within each time interval. The derived approximations are studied in a numerical test and compared to other available expressions. The sixth order expression is applied to …

Modeling Hydroxide In Classical Proton Hopping Simulations And Amyloid Beta Membrane Pores, Ankita Dutta

Dissertations, Theses, and Capstone Projects

H3O+ and OH- ions display anomalously large diffusion coefficients, a property that is often attributed to their ability to perform structural diffusion which allow these ions to move through aqueous solutions by sequential proton transfers, also known as ‘Grotthuss hopping’. A rearrangement of the local solvation structure is known to be the prerequisite for proton transfer events via these ions. Studying this phenomenon using classical molecular dynamics simulations that do not allow bond rearrangements poses significant obstacles. Here we use a Monte Carlo augmented classical Molecular Dynamics method called the MOBHY algorithm which allows instantaneous changes in protonation states in …

Evaluating The Reliability And Accuracy Of Alchemical Binding Free Energy Methods And Calculations, Fnu Sheenam

Dissertations, Theses, and Capstone Projects

Molecular recognition plays a crucial role in various biological processes, such as enzymatic reactions, signal transduction, and genetic information processing. Investigating how proteins selectively bind to their partners is an active research area, but there is a lack of experimental details on protein structures and interactions in molecular complexes. Computational techniques based on macromolecular structures offer a way to predict protein-ligand interactions and explore their recognition mechanisms. Estimating binding affinities, particularly through alchemical binding free energy calculations, has become valuable in supporting drug discovery. This work introduces new methodologies, utilizing the Alchemical Transfer Method, to address issues like poor convergence …

Rational Design Of Peptide-Based Materials Informed By Multiscale Molecular Dynamics Simulations, Dhwanit Rahul Dave

Dissertations, Theses, and Capstone Projects

The challenge of establishing a sustainable and circular economy for materials in medicine and technology necessitates bioinspired design. Nature's intricate machinery, forged through evolution, relies on a finite set of biomolecular building blocks with through-bond and through-space interactions. Repurposing these molecular building blocks requires a seamless integration of computational modeling, design, and experimental validation. The tools and concepts developed in this thesis pioneer new directions in peptide-materials design, grounded in fundamental principles of physical chemistry. We present a synergistic approach that integrates experimental designs and computational methods, specifically molecular dynamics simulations, to gain in-depth molecular insights crucial for advancing the …

Quantifying Temperature-, Pressure-, And Nuclear Quantum Effects On Hydrophobic And Hydrophilic Water-Mediated Interactions, Justin T. Engstler

Dissertations, Theses, and Capstone Projects

Water-mediated interactions (WMIs) are responsible for diverse processes in aqueous solutions, including protein folding and nanoparticle aggregation. WMI may be affected by changes in temperature and pressure, and hence, they can alter chemical/physical processes that occur in aqueous environments. Traditionally, attention has been focused on hydrophobic interactions while, in comparison, the role of hydrophilic and hybrid (hydrophobic–hydrophilic) interactions have been mostly overlooked. Here, we study the role of T and P on the WMI between nanoscale (i) hydrophobic–hydrophobic, (ii) hydrophilic–hydrophilic, and (iii) hydrophilic–hydrophobic pairs of (hydroxylated/non-hydroxylated) graphene-based surfaces. We find that hydrophobic, hydrophilic, and hybrid interactions are all sensitive to …

Singlet Oxygen-Mediated Conformational Flexibility, Antioxidant, And Isomerization Studies In Chemistry And Biochemistry, Oliver Turque

Dissertations, Theses, and Capstone Projects

Three chapters are included in this dissertation, each of which describes non-oxidative reactions, with peroxy intermediates formed between singlet oxygen (¹O₂) and substrate. (1) Novel discoveries related to the intermediate formed by ¹O₂ and dimethyl disulfane are explored. (2) A new mechanism is proposed, wherein the dihedral angle CS–SC (θ) determines the pro- or antioxidant activity of an organic disulfide. (3) A review of ¹O₂'s ability to facilitate the geometric isomerization of alkenes and polyenes is presented in Chapter 3.

Chapter 1 investigates the role of singlet oxygen potentially …