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Full-Text Articles in Biophysics

Amyloid Fibril Formation And Polymorphism : A Critical Role Of Sulfur-Containing Amino Acid Residues, Tatiana Quiñones-Ruiz Aug 2022

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 …


Molecular Simulation Of Rna Conformational Dynamics : An Example Of Micro-Rna Targeting Messenger Rna : Mir-34a-Msirt1, Parisa Ebrahimi Aug 2021

Molecular Simulation Of Rna Conformational Dynamics : An Example Of Micro-Rna Targeting Messenger Rna : Mir-34a-Msirt1, Parisa Ebrahimi

Legacy Theses & Dissertations (2009 - 2024)

MicroRNA (miRNA), as a distinct class of biological regulators and a ”guide” member of non-coding RNA-protein complexes (RNPs), regulates more than 60% of protein-coding genes expression through base-pairing with targeted messenger RNA (mRNA) in the RNA-Induced Silencing Complex (RISC). Most of miRNAs identified in human, are conserved in other animals, which have preferentially conserved interaction sites particularly in 3’ untranslated regions (3’UTRs) of many human messenger mRNAs.The capability of a single miRNA to target more than hundreds of mRNAs, suggests that miRNAs influence essentially all developmental process and diseases, which also makes them interesting candidates as therapeutics agents. The primary …


Molecular Simulation Of Rna Conformational Dynamics : An Example Of Micro-Rna Targeting Messenger Rna : Mir-34a-Msirt1, Parisa Ebrahimi Aug 2021

Molecular Simulation Of Rna Conformational Dynamics : An Example Of Micro-Rna Targeting Messenger Rna : Mir-34a-Msirt1, Parisa Ebrahimi

Legacy Theses & Dissertations (2009 - 2024)

MicroRNA (miRNA), as a distinct class of biological regulators and a ”guide” member of non-coding RNA-protein complexes (RNPs), regulates more than 60% of protein-coding genes expression through base-pairing with targeted messenger RNA (mRNA) in the RNA-Induced Silencing Complex (RISC). Most of miRNAs identified in human, are conserved in other animals, which have preferentially conserved interaction sites particularly in 3’ untranslated regions (3’UTRs) of many human messenger mRNAs.The capability of a single miRNA to target more than hundreds of mRNAs, suggests that miRNAs influence essentially all developmental process and diseases, which also makes them interesting candidates as therapeutics agents. The primary …


Study Of Primary Cilium Structure And Intraflagellar Transport, Shufeng Sun Jan 2021

Study Of Primary Cilium Structure And Intraflagellar Transport, Shufeng Sun

Legacy Theses & Dissertations (2009 - 2024)

Primary cilia are hair-like protrusions that stem from the basal bodies in the cytoplasm and extend into the extracellular space to sense signals. Intraflagellar transport (IFT) functions to transport cargo molecules into and out of the ciliary compartment to assemble, maintain, and disassemble the cilia. Accurate knowledge of the three-dimensional (3D) structure of primary cilia and precise details of the IFT profile is the foundation for understanding the sensory functions of primary cilia. This work covers three aspects of primary cilia. Firstly, we obtained and analyzed the overall 3D architecture of the complete primary cilia axoneme region using serial section …


Significance Of Rna 2'-5' Linkage And Metal-Ion Mediated Base Pairs, Fusheng Shen Jan 2019

Significance Of Rna 2'-5' Linkage And Metal-Ion Mediated Base Pairs, Fusheng Shen

Legacy Theses & Dissertations (2009 - 2024)

It has been known that the template-directed RNA chemical replication reaction produces mixture of backbones containing both 3’-5’ and 2’-5’ linkages. This backbone heterogeneity has been a significant problem in studying the emergence of RNA World from the prebiotic chemistry. However, very recently, it is reported that FMN binding aptamer and a hammerhead ribozyme are still able to retain considerable functions in the presence of certain 2’-5’ linkages, indicating that RNA backbones may be quite flexible and this backbone heterogeneity problem may not be as severe as originally thought. This finding also brings two related important questions: First, how does …


Multifunctional Nanomaterials Utilizing Hybridization Chain Reaction For Molecular Diagnostics And Bioanalytical Applications, Md Muhit Rana Jan 2017

Multifunctional Nanomaterials Utilizing Hybridization Chain Reaction For Molecular Diagnostics And Bioanalytical Applications, Md Muhit Rana

Legacy Theses & Dissertations (2009 - 2024)

DNA nanotechnology has shown great promise in molecular diagnostic, bioanalytical and biomedical applications. The great challenge of detecting target analytes, biomarkers and small molecules, in molecular diagnostics is low yield sensitivity. To address this challenge, different nanomaterials have been used for a long time and to date there is no such cost-effective bioanalytical technique which can detect these target biomarkers (DNA, RNA, circulating DNA/miRNA) or environmental heavy metal ions (Hg2+ and Ag+) in a cost-effective and efficient manner.


Bayesian Signal Detection And Source Separation In Simulated Brain Computer Interface Systems, Muhammad Asim Mubeen Jan 2016

Bayesian Signal Detection And Source Separation In Simulated Brain Computer Interface Systems, Muhammad Asim Mubeen

Legacy Theses & Dissertations (2009 - 2024)

The problems of signal detection and source separation are important in many fields of science and engineering. In many cases, a target signal needs to be detected in real time and is contaminated by noise. Sometimes the level of noise is on the order of the signal itself. The real time detection of a target signal is of key importance in problems such as the brain computer interface systems. In brain computer interface systems, the neural activity (electric signals) of the brain is detected using sensors (electrodes) on the surface of the brain or the scalp. This signal is contaminated …


The Structural Heterogeneity And Dynamics Of Base Stacking And Unstacking In Nucleic Acids, Ada Anna Sedova Jan 2015

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 …


Structure And Stability Of Amyloid Fibrils Studied By Advanced Vibrational Spectroscopy, Marudachalam Shanmugasundaram Jan 2015

Structure And Stability Of Amyloid Fibrils Studied By Advanced Vibrational Spectroscopy, Marudachalam Shanmugasundaram

Legacy Theses & Dissertations (2009 - 2024)

Protein misfolding often leads to the formation of refractory protein aggregates like amyloid fibrils. These fibrils possess a highly ordered structure and are implicated in over 25 severe diseases including Alzheimer’s, Parkinson’s and prion diseases. This work was focused on understanding the morphology and conformation of amyloid fibrils and their stability after formation. The deconstruction of fibrils as well as other aggregates like inclusion bodies under mild conditions was also investigated using Archaeal chaperones.


Probing Secondary And Tertiary Rna Folding Using Force And Temperature, William Stephenson Jan 2014

Probing Secondary And Tertiary Rna Folding Using Force And Temperature, William Stephenson

Legacy Theses & Dissertations (2009 - 2024)

RNA folding is the process whereby a single stranded RNA molecule assumes its three-dimensional functional conformation. Along with the protein folding problem, the RNA folding problem remains as one of the great unsolved problems in biophysics. Generally RNA folding occurs in a hierarchical manner whereby the sequence of an RNA (primary structure) determines which regions will form helical segments (secondary structure) before further rearrangement and base pairing of secondary structure motifs (tertiary structure). Due to the intimate connection between structure and function within molecular biology, increased familiarity with the thermodynamic and kinetic factors that govern RNA folding will permit the …


Structure-Activity Relationship Of 2,3-Benzodiazepin-4-Ones As Noncompetitive Ampa Receptor Antagonists, Mohammad Shaban Qneibi Jan 2013

Structure-Activity Relationship Of 2,3-Benzodiazepin-4-Ones As Noncompetitive Ampa Receptor Antagonists, Mohammad Shaban Qneibi

Legacy Theses & Dissertations (2009 - 2024)

2,3-Benzodiazepin-4-one (BDZ-11) derivatives are a special group of 2,3-benzodiazepine compounds. These compounds have been previously synthesized as AMPA receptor inhibitors, and they are also potential drugs for the treatment of various neurological diseases involving excessive AMPA receptor activity. AMPA receptors are a subtype of glutamate ion channel proteins and are responsible for the majority of excitatory neurotransmission in the mammalian central nervous system. Specifically, they are critically involved in neuronal development and brain activities, including learning and memory. Overstimulation of AMPA receptors is associated with some neurological diseases such as ALS, stroke and Alzheimer's disease. Despite the fact that hundreds …


Characterizing The Effects Of Glutaraldehyde On The Ryanodine Receptor Calcium Release Channel, Joshua Dov Strauss Jan 2013

Characterizing The Effects Of Glutaraldehyde On The Ryanodine Receptor Calcium Release Channel, Joshua Dov Strauss

Legacy Theses & Dissertations (2009 - 2024)

Ryanodine receptors (RyR) are large intracellular calcium release channels, which


Y-Family Dna Polymerases : Mechanism Of Single-Base Deletion And Effect Of Pcna Interaction, Yifeng Wu Jan 2013

Y-Family Dna Polymerases : Mechanism Of Single-Base Deletion And Effect Of Pcna Interaction, Yifeng Wu

Legacy Theses & Dissertations (2009 - 2024)

Translesional synthesis (TLS) by specialized Y-family DNA polymerases is a DNA damage tolerance pathway to bypass DNA lesions that have not been repaired by other DNA repair mechanisms. Despite their valuable lesion bypass ability, the Y-family DNA polymerases display a much lower fidelity upon replicating undamaged DNA. Their activity therefore needs to be well regulated in the cell. In our first project, we examined how an archaeal Y-family DNA polymerase, Dpo4, makes single-base deletions during replication. Dpo4 belongs to the DinB subfamily which is known to make single-base deletions. Although previous studies suggested that it uses a dNTP-stabilized misalignment mechanism, …


Structural And Functional Characterization Of Dna Polymerase Ss Mutator Mutants, Sneha Rangarajan Jan 2012

Structural And Functional Characterization Of Dna Polymerase Ss Mutator Mutants, Sneha Rangarajan

Legacy Theses & Dissertations (2009 - 2024)

DNA Polymerase ß (polß) plays a crucial role in repairing damaged DNA in a process called Base Excision Repair (BER). BER is a major pathway of DNA repair, making this system absolutely vital for maintaining genomic integrity. Recent studies estimate 30% of human tumors to contain polß variants that led us to believe that there is a high degree of association between mutations in polß and cancer. In this pathway, after recognition and excision of the damaged base, the DNA is cleaved at an apurinic (AP) site by AP endonuclease leaving behind a 3' hydroxyl and 5' deoxyribose phosphate (dRP). …


Homologous And Heterologous Crystallin Protein Interactions As The Molecular Basis Of Inherited Cataract, Priya Ranjan Banerjee Jan 2011

Homologous And Heterologous Crystallin Protein Interactions As The Molecular Basis Of Inherited Cataract, Priya Ranjan Banerjee

Legacy Theses & Dissertations (2009 - 2024)

Age-related cataract is the most common cause of blindness worldwide. Nearly fifty percent of Americans above the age of 75 are diagnosed with this disease (http://www.nei.nih.gov/eyedata/pbd_tables.asp), and surgical intervention is the sole method of treatment at present (http://www.nei.nih.gov/healthyvision/objective/cataracts.asp). In the developing world, even this treatment is not readily available. These are compelling reasons to search for better treatments to delay, prevent or arrest cataract formation. Recent evidence suggests that age-related cataracts also have a genetic component. Therefore, determining the mechanisms underlying genetic cataracts with a known association to a protein-mutation is one important strategy towards understanding the molecular basis for …


Study Of Dynamic Processes In Protein Synthesis Using Heterogeneous Ribosome Specimens, Jie Fu Jan 2009

Study Of Dynamic Processes In Protein Synthesis Using Heterogeneous Ribosome Specimens, Jie Fu

Legacy Theses & Dissertations (2009 - 2024)

Single-particle reconstruction from cryo-electron microscopy (cryo-EM) images is a widely used technique in studying the structure of macromolecular complexes. This technique allows the visualization of molecules in their native hydrated state. The heterogeneity of two-dimensional projection images, resulting from the co-existence of different states of a macromolecular complex, remains a major obstacle, as it impairs the validity of reconstruction and limits the progress toward higher resolution. On the other hand, co-existing structures, if successfully extracted from a single dataset, can provide valuable information about the equilibrium and dynamics of the biological system being studied.