Biochemistry, Biophysics, and Structural Biology Commons^™

Evaluation Of The Genetic And Structural Variations Of Camel Hemoglobin, Amanat Ali

Dissertations

The single-humped Arabian camel (Camelus dromedarius) thrives in the hot arid Arabian desert. Many unique adaptations permit it to accomplish this. Camel erythrocytes or red blood cells (RBCs) have a peculiar elliptical shape and are amenable to large variations in physical conditions resulting from dehydration and rehydration cycles. The oxygen transport protein hemoglobin is found abundantly in RBCs and is also believed to behave differently in camels. While several physiological and biochemical studies have been performed on camel hemoglobin, very little is known about genetic and structural adaptions in this protein. The camel genome harbors several unique variations …

Ionophoric Polyphenols Are Permeable To The Blood Brain Barrier, Interact With Human Serum Albumin And Calf Thymus Dna, And Inhibit Ache Enzymatic Activity, Alberto Martinez, Mai Zahran, Miguel Gomez, Johnny Guevara, Rosemary Pichardo-Bueno, Junaid Asim, Gabriel Ortiz, Yaa Andoh, Sinji Shibutani, Baljit Kaur

Publications and Research

Alzheimer’s disease (AD) is the most common form of dementia that affects more than 40 million people around the world. The incidence is expected to rapidly increase due to the lack of any effective treatment. In previous work we synthesized a family of five ionophoric polyphenols (compounds 1–5) that targeted important aspects related to AD, such as the toxic aggregation of amyloid-β peptides, the production of reactive oxygen species, or the excessive presence of Cu²⁺ ions. Here, in order to gain insights into their potential therapeutic value, we have tested the ability of compounds 1– …

Network Approaches To Elucidate The Determinants Of Protein Topology And Stability, Zeinab Haratipour

Chemistry & Biochemistry Theses & Dissertations

Predicting three-dimensional structures of proteins from sequence information alone, remains one of the most profoundly challenging and intensely studied problems in basic science. It has uniquely garnered the interdisciplinary efforts of biologists, biochemists, computer scientists, mathematicians and physicists. The advancement of computational methods to study fundamental features of proteins also enables insights that are either difficult to explore experimentally or complimentary to further interpret experimental data. In the present research and through the combined development and application of molecular dynamics and network science approaches we aimed to elucidate the role of geographically important amino acids and evolutionarily conserved long-range interactions …

Amyloid Proteins And Fibrils Stability, Farbod Mahmoudinobar

Dissertations

Compared to globular proteins that have a stable native structure, intrinsically disordered peptides (IDP) sample an ensemble of structures without folding into a native conformation.One example of IDP is the amyloid-beta(Abeta) protein which is the main constituent of senile plaques in the brain of Alzheimer's patients.Understanding the process by which IDPs undergo structural changes to form oligomers that eventually aggregate into senile plaques/amyloid fibrils may significantly advance the development of novel therapeutic methods to treat neurodegenerative diseases, for which there is no cure to date. This dissertation has two main objectives. The first one is to investigate and identify structural …

Fast-Forward Protein Folding And Design: Development, Analysis, And Applications Of The Fast Sampling Algorithm, Maxwell Isaac Zimmerman

Arts & Sciences Electronic Theses and Dissertations

Molecular dynamics simulations are a powerful tool to explore conformational landscapes, though limitations in computational hardware commonly thwart observation of biologically relevant events. Since highly specialized or massively parallelized distributed supercomputers are not available to most scientists, there is a strong need for methods that can access long timescale phenomena using commodity hardware. In this thesis, I present the goal-oriented sampling method, Fluctuation Amplification of Specific Traits (FAST), that takes advantage of Markov state models (MSMs) to adaptively explore conformational space using equilibrium-based simulations. This method follows gradients in conformational space to quickly explore relevant conformational transitions with orders of …

A Physics-Based Intermolecular Potential For Biomolecular Simulation, Joshua Andrew Rackers

Arts & Sciences Electronic Theses and Dissertations

The grand challenge of biophysics is to use the fundamental laws of physics to predict how biological molecules will move and interact. The atomistic HIPPO (Hydrogen-like Intermolecular Polarizable Potential) force field is meant to address this challenge. It does so by breaking down the intermolecular potential energy function of biomolecular interactions into physically meaningful components (electrostatics, polarization, dispersion, and exchangerepulsion) and using this function to drive molecular dynamics simulations. This force field is able to achieve accuracy within 1 kcal/mol for each component when compared with ab initio Symmetry Adapted Perturbation Theory calculations. HIPPO is capable of this accuracy because …

Multiscale Simulations Of Intrinsically Disordered Proteins, Xiaorong Liu

Doctoral Dissertations

Intrinsically disordered proteins (IDPs) lack stable secondary and/or tertiary structures under physiological conditions. The have now been recognized to play important roles in numerous biological processes, particularly cellular signaling and regulation. Mutation of IDPs are frequently associated with human diseases, such as cancers and neuron degenerative diseases. Therefore, it is important to understand the structure, dynamics, and interactions of IDPs, so as to establish the mechanistic basis of how intrinsic disorder mediates versatile functions and how such mechanisms may fail in human diseases. However, the heterogeneous structural ensembles of IDPs are not amenable to high resolution characterization solely through experimental …

Impact Of Conformational Change, Solvation Environment, And Post-Translational Modification On Desulfurization Enzyme 2'-Hydroxybiphenyl-2-Sulfinate Desulfinase (Dszb) Stability And Activity, Landon C. Mills

Theses and Dissertations--Chemical and Materials Engineering

Naturally occurring enzymatic pathways enable highly specific, rapid thiophenic sulfur cleavage occurring at ambient temperature and pressure, which may be harnessed for the desulfurization of petroleum-based fuel. One pathway found in bacteria is a four-step catabolic pathway (the 4S pathway) converting dibenzothiophene (DBT), a common crude oil contaminant, into 2-hydroxybiphenyl (HBP) without disrupting the carbon-carbon bonds. 2’-Hydroxybiphenyl-2-sulfinate desulfinase (DszB), the rate-limiting enzyme in the enzyme cascade, is capable of selectively cleaving carbon-sulfur bonds. Accordingly, understanding the molecular mechanisms of DszB activity may enable development of the cascade as industrial biotechnology. Based on crystallographic evidence, we hypothesized that DszB …

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 …

Structure-Function Relationships In Hexacoordinate Heme Proteins: Mechanism Of Cytoglobin Interactions With Exogenous Ligands, Antonija Tangar

FIU Electronic Theses and Dissertations

Cytoglobin (Cygb) and neuroglobin (Ngb) are among the newest members of vertebrate globin family characterized by a classical 3-over-3 α-helical fold and a heme prosthetic group capable of reversibly binding small ligands such as O₂, CO and NO. The physiological functions of Cygb and Ngb remain to be determined; however, current data suggest that both proteins have a significant role in cytoprotection in hypoxic and genotoxic conditions. Cytoglobin and Ngb are distinct from their better-known counterparts, hemoglobin (Hb) and myoglobin (Mb), in several structural features. First, in the absence of an external ligand, the sixth coordination site of …

Hard-Sphere-Like Dynamics In Highly Concentrated Alpha-Crystallin Suspensions, Preeti Vodnala, Laurence Lurio, Michael C. Vega, Elizabeth Gaillard

Faculty Peer-Reviewed Publications

The dynamics of concentrated suspensions of the eye-lens protein alpha crystallin have been measured using x-ray photon correlation spectroscopy. Measurements were made at wave vectors corresponding to the first peak in the hard-sphere structure factor and volume fractions close to the critical volume fraction for the glass transition. Langevin dynamics simulations were also performed in parallel to the experiments. The intermediate scattering function f(q,τ) could be fit using a stretched exponential decay for both experiments and numerical simulations. The measured relaxation times show good agreement with simulations for polydisperse hard-sphere colloids.

Understanding Carbohydrate Recognition Mechanisms In Non-Catalytic Proteins Through Molecular Simulations, Abhishek A. Kognole

Theses and Dissertations--Chemical and Materials Engineering

Non-catalytic protein-carbohydrate interactions are an essential element of various biological events. This dissertation presents the work on understanding carbohydrate recognition mechanisms and their physical significance in two groups of non-catalytic proteins, also called lectins, which play key roles in major applications such as cellulosic biofuel production and drug delivery pathways. A computational approach using molecular modeling, molecular dynamic simulations and free energy calculations was used to study molecular-level protein-carbohydrate and protein-protein interactions. Various microorganisms like bacteria and fungi secret multi-modular enzymes to deconstruct cellulosic biomass into fermentable sugars. The carbohydrate binding modules (CBM) are non-catalytic domains of such enzymes that …

Computational Investigation Of The Pore Formation Mechanism Of Beta-Hairpin Antimicrobial Peptides, Richard Lipkin

Dissertations, Theses, and Capstone Projects

β-hairpin antimicrobial peptides (AMPs) are small, usually cationic peptides that provide innate biological defenses against multiple agents. They have been proposed as the basis for novel antibiotics, but their pore formation has not been directly observed on a molecular level. We review previous computational studies of peptide-induced membrane pore formation and report several new molecular dynamics simulations of β-hairpin AMPs to elucidate their pore formation mechanism. We simulated β-barrels of various AMPs in anionic implicit membranes, finding that most of the AMPs’ β-barrels were not as stable as those of protegrin. We also performed an optimization study of protegrin β-barrels …

Improving The Thermal Stability Of Cellobiohydrolase Cel7a From Hypocrea Jecorina By Directed Evolution, Frits Goedegebuur, Lydia Dankmeyer, Peter Gualfetti, Saeid Karkehabadi, Henrik Hansson, Suvamay Jana, Vicky Huynh, Bradley R. Kelemen, Paulien Kruithof, Edmund A. Larenas, Pauline J. M. Teunissen, Jerry Ståhlberg, Christina M. Payne, Colin Mitchinson, Mats Sandgren

Chemical and Materials Engineering Faculty Publications

Secreted mixtures of Hypocrea jecorina cellulases are able to efficiently degrade cellulosic biomass to fermentable sugars at large, commercially relevant scales. H. jecorina Cel7A, cellobiohydrolase I, from glycoside hydrolase family 7, is the workhorse enzyme of the process. However, the thermal stability of Cel7A limits its use to processes where temperatures are no higher than 50 °C. Enhanced thermal stability is desirable to enable the use of higher processing temperatures and to improve the economic feasibility of industrial biomass conversion. Here, we enhanced the thermal stability of Cel7A through directed evolution. Sites with increased thermal stability properties were combined, and …

Studies Into The Structure And Function Of Various Domains Of Obscurin And Titin, Rachel A. Policke

Senior Honors Projects, 2010-2019

Muscles give our bodies the ability to move by stretching and contracting. While contraction is accomplished by the well-known actin-myosin interaction, not much is known about stretch. Two integral muscle proteins involved in stretch are titin and obscurin; both are long rope-like protein molecules that seem to act as molecular springs. Mutations in these two proteins can lead to diseases such as hypertrophic cardiomyopathy and muscular dystrophy, as well as a variety of cancers. In an effort to understand muscle stretch and signaling on a more fundamental level, here we present the high resolution structure of obscurin Ig59, a domain …

Computing Spatiotemporal Heat Maps Of Lipid Electropore Formation: A Statistical Approach, Willy Wriggers, Frederica Castellani, Julio A. Kovacs, P. Thomas Vernier

Mechanical & Aerospace Engineering Faculty Publications

We extend the multiscale spatiotemporal heat map strategies originally developed for interpreting molecular dynamics simulations of well-structured proteins to liquids such as lipid bilayers and solvents. Our analysis informs the experimental and theoretical investigation of electroporation, that is, the externally imposed breaching of the cell membrane under the influence of an electric field of sufficient magnitude. To understand the nanoscale architecture of electroporation, we transform time domain data of the coarse-grained interaction networks of lipids and solvents into spatial heat maps of the most relevant constituent molecules. The application takes advantage of our earlier graph-based activity functions by accounting for …

Modeling The Binding Of Neurotransmitter Transporter Inhibitors With Molecular Dynamics And Free Energy Calculations, Bernandie Jean

Electronic Theses and Dissertations

The monoamine transporter (MAT) proteins responsible for the reuptake of the neurotransmitter substrates, dopamine, serotonin, and norepinephrine, are drug targets for the treatment of psychiatric disorders including depression, anxiety, and attention deficit hyperactivity disorder. Small molecules that inhibit these proteins can serve as useful therapeutic agents. However, some dopamine transporter (DAT) inhibitors, such as cocaine and methamphetamine, are highly addictive and abusable. Efforts have been made to develop small molecules that will inhibit the transporters and elucidate specific binding site interactions. This work provides knowledge of molecular interactions associated with MAT inhibitors by offering an atomistic perspective that can guide …

Group I Intron Internal Guide Sequence Binding Strength As A Component Of Ribozyme Network Formation, Elizabeth Satterwhite, Jessica Anne Mellor Yeates, Niles Lehman

Chemistry Faculty Publications and Presentations

Origins-of-life research requires searching for a plausible transition from simple chemicals to larger macromolecules that can both hold information and catalyze their own production. We have previously shown that some group I intron ribozymes possess the ability to help synthesize other ribozyme genotypes by recombination reactions in small networks in an autocatalytic fashion. By simplifying these recombination reactions, using fluorescent anisotropy, we quantified the thermodynamic binding strength between two nucleotides of two group I intron RNA fragments for all 16 possible genotype combinations. We provide evidence that the binding strength (K_D) between the 3-nucleotide internal guide sequence …

Insights From Molecular Dynamics On Substrate Binding And Effects Of Active Site Mutations In Delta1-Pyrroline-5-Carboxylate Dehydrogenase, Bogdan F. Ion, Mohamed M. Aboelnga, James W. Gauld

Chemistry and Biochemistry Publications

The NAD+-dependent enzyme, 1-pyrroline-5-carboxylate dehydrogenase (P5CDH), has an important role in proline and hydroxyproline catabolism for humans. Specifically, this aldehyde dehydrogenase is responsible for the oxidation of both L-glutamate- -semialdehyde (GSA) and 4-erythro-hydroxy-L-glutamate- -semialdehyde (4-OH-GSA) to their respective L-glutamate product forms. We have performed a detailed molecular dynamics (MD) study of both the reactant and product complex structures of P5CDH to gain insights into ligand binding (i.e., GSA, 4-OH-GSA, NAD+, GLU) in the active site. Moreover, our investigations were further extended to examine the structural impact of S352L, S352A, and E314A mutations on the deficiency in the P5CDH enzymatic activity. …

Computational Modeling Of Allosteric Stimulation Of Nipah Virus Host Binding Protein, Priyanka Dutta

USF Tampa Graduate Theses and Dissertations

Nipah belongs to the family of paramyxoviruses that cause numerous fatal diseases in humans and farm animals. There are no FDA approved drugs for Nipah or any of the paramyxoviruses. Designing antiviral therapies that are more resistant to viral mutations require understanding of molecular details underlying infection. This dissertation focuses on obtaining molecular insights into the very first step of infection by Nipah. Such details, in fact, remain unknown for all paramyxoviruses. Infection begins with the allosteric stimulation of Nipah virus host binding protein by host cell receptors. Understanding molecular details of this stimulation process have been challenging mainly because, …

Stability Of Norwalk Virus Capsid Protein Interfaces Evaluated By In Silico Nanoindentation, Prakhar Bansal

University Scholar Projects

Studying the mechanical properties of viral capsids can give several insights into not only the lifecycle of the virus, but also into potential drug targets to thwart the progression of viral infection. Nanoindentation using an atomic force microscope is a useful technique for determining structural properties of small molecules and particles, and is commonly used to study viral capsids. This technique utilizes the probe of the microscope to push down on the capsid and record the forces along the indentation path. We ran this experiment in silico where we simulated the nanoindentation of Norwalk virus capsids using molecular dynamics. Running …

Computational Investigations Into The Molecular Underpinnings Of Eyesight Signaling Pathways, Shaan Kamal

University Scholar Projects

Phosphodiesterase 6 (PDE6) is a critical enzyme in the eyesight-signaling pathway. When activated, PDE6 hydrolyzes cGMP to GMP, which deactivates cGMP- gated ion channels, causing hyperpolarization of the cell and activating the sensory neurons responsible for vision. Within the PDE family, PDE6 is the only enzyme known to have an inhibitory subunit (PDE6-γ), which allows for the regulation of cGMP levels. When PDE6-γ is bound to PDE6, the enzyme is turned “off” and cannot catalyze cGMP. The α subunit of the G-protein transducin removes PDE6-γ and activates PDE6. PDE6 has proven problematic to isolate, making it difficult to study experimentally …

Studies Into The Allosteric Regulation Of Adp-Glucose Pyrophosphorylases, Benjamin Luke Hill

Dissertations

The synthesis of glycogen in bacteria and starch in plants is allosterically controlled by the production of ADP-glucose by ADP-glucose pyrophosphorylase. Using computational studies, site directed mutagenesis, and kinetic characterization, and protein crystallography we found a critical region for transmitting the allosteric signal in the Escherichia coli and A. tumefaciens ADP-glucose pyrophosphorylase. Molecular dynamics simulations and structural comparisons with other ADP-glucose pyrophosphorylases provided information to hypothesize communication pathways that link allosteric and active sites, and this was tested by site-directed mutagenesis and kinetic characterization of the mutant enzymes. In addition, the application of x-ray crystallography enabled the pinpointing of the …

A Five Residue Insertion Between Codons 28 And 29 Of The Hiv-1 Protease Gene Reduces The Replicative Capacity Of The Virus, Cathy Mcleod

Wayne State University Theses

HIV-1 protease (PR) is a 99 amino acid protein responsible for cleavage of the viral polyprotein. We have identified a novel clinical isolate, MDR/28, which contains a five residue insertion between codons 28 and 29 of a multi-drug resistant (MDR) PR. This clinical isolate displays reduced viral replicative capacity compared to the wild-type. As opposed to drug-resistance mutations, studies on insertions remain largely underrepresented in the literature, and the consequences of such insertions are largely unknown. To understand the mechanism leading to reduced replicative capacity, three PR models were created and subjected to 40ns molecular dynamics simulations: MDR/28, wild type, …

Computational Modeling Of Rna-Small Molecule And Rna-Protein Interactions, Lu Chen

Dissertations & Theses (Open Access)

The past decade has witnessed an era of RNA biology; despite the considerable discoveries nowadays, challenges still remain when one aims to screen RNA-interacting small molecule or RNA-interacting protein. These challenges imply an immediate need for cost-efficient while predictive computational tools capable of generating insightful hypotheses to discover novel RNA-interacting small molecule or RNA-interacting protein. Thus, we implemented novel computational models in this dissertation to predict RNA-ligand interactions (Chapter 1) and RNA-protein interactions (Chapter 2).

Targeting RNA has not garnered comparable interest as protein, and is restricted by lack of computational tools for structure-based drug design. To test the potential …

Picosecond To Terahertz Perturbation Of Interfacial Water And Electropermeabilization Of Biological Membranes, P. Thomas Vernier, Zachary A. Levine, Ming-Chak Ho, Shu Xiao, Iurii Semenov, Andrei G. Pakhomov

Bioelectrics Publications

Non-thermal probing and stimulation with subnanosecond electric pulses and terahertz electromagnetic radiation may lead to new, minimally invasive diagnostic and therapeutic procedures and to methods for remote monitoring and analysis of biological systems, including plants, animals, and humans. To effectively engineer these still-emerging tools, we need an understanding of the biophysical mechanisms underlying the responses that have been reported to these novel stimuli. We show here that subnanosecond (≤500 ps) electric pulses induce action potentials in neurons and cause calcium transients in neuroblastoma-glioma hybrid cells, and we report complementary molecular dynamics simulations of phospholipid bilayers in electric fields in which …

The Structural Heterogeneity And Dynamics Of Base Stacking And Unstacking In Nucleic Acids, Ada Anna Sedova

Legacy Theses & Dissertations (2009 - 2024)

Base stacking provides stability to nucleic acid duplexes, and base unstacking is involved in numerous biological functions related to nucleic acids, including replication, repair, transcription, and translation. The patterns of base stacking and unstacking in available nucleic acid crystal structures were classified after separation into their individual single strand dinucleotide components and clustering using a k-means-based ensemble clustering method. The A- and B-form proximity of these dinucleotide structures were assessed to discover that RNA dinucleotides can approach B-form-like structures. Umbrella sampling molecular dynamics simulations were used to obtain the potential of mean force profiles for base unstacking at 5'-termini for …

Automatic Animation Of Molecular Motion Using Python And Cinema 4d, Diana Zajac, Nathaniel Smith, Dan Gurnon

Annual Student Research Poster Session

No abstract provided.

Tracing Beta Strands Using Strandtwister From Cryo-Em Density Maps At Medium Resolutions, Dong Si, Jing He

Computer Science Faculty Publications

Major secondary structure elements such as α helices and β sheets can be computationally detected from cryoelectron microscopy (cryo-EM) density maps with medium resolutions of 5–10 A˚ . However, a critical piece of information for modeling atomic structures is missing, because there are no tools to detect β strands from cryo-EM maps at medium resolutions. We propose a method, StrandTwister, to detect the traces of β strands through the analysis of twist, an intrinsic nature of a β sheet. StrandTwister has been tested using 100 β sheets simulated at 10 A˚ resolution and 39 β sheets computationally detected from cryo-EM …

Evaluations Of A Mechanistic Hypothesis For The Influence Of Extracellular Ions On Electroporation Due To High-Intensity, Nanosecond Pulsing, V. Sridhara, R. P. Joshi

Electrical & Computer Engineering Faculty Publications

The effect of ions present in the extracellular medium on electroporation by high-intensity, short-duration pulsing is studied through molecular dynamic simulations. Our simulation results indicate that mobile ions in the medium might play a role in creating stronger local electric fields across membranes that then reinforce and strengthen electroporation. Much faster pore formation is predicted in higher conductivity media. However, the impact of extracellular conductivity on cellular inflows, which depend on transport processes such as electrophoresis, could be different as discussed here. Our simulation results also show that interactions between cations (Na+ in this case) and the carbonyl oxygen of …