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Doctoral Dissertations

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Development Of An Integrated Workflow For Nucleosome Modeling And Simulations, Ran Sun Mar 2024

Development Of An Integrated Workflow For Nucleosome Modeling And Simulations, Ran Sun

Doctoral Dissertations

Nucleosomes are the building blocks of eukaryotic genomes and thus fundamental to to all genetic processes. Any protein or drug that binds DNA must either cooperate or compete with nucleosomes. Given that a nucleosome contains 147 base pairs of DNA, there are approximately 4^147 or 10^88 possible sequences for a single nucleosome. Exhaustive studies are not possible. However, genome wide association studies can identify individual nucleosomes of interest to a specific mechanism, and today's supercomputers enable comparative simulation studies of 10s to 100s of nucleosomes. The goal of this thesis is to develop and present and end-to-end workflow that serves …


Atomistic Simulations Of Intrinsically Disordered Protein Folding And Dynamics, Xiping Gong Nov 2023

Atomistic Simulations Of Intrinsically Disordered Protein Folding And Dynamics, Xiping Gong

Doctoral Dissertations

Intrinsically disordered proteins (IDPs) are crucial in biology and human diseases, necessitating a comprehensive understanding of their structure, dynamics, and interactions. Atomistic simulations have emerged as a key tool for unraveling the molecular intricacies and establishing mechanistic insights into how these proteins facilitate diverse biological functions. However, achieving accurate simulations requires both an appropriate protein force field capable of describing the energy landscape of functionally relevant IDP conformations and sufficient conformational sampling to capture the free energy landscape of IDP dynamics. These factors are fundamental in comprehending potential IDP structures, dynamics, and interactions. I first conducted explicit solvent simulations to …


A Novel Transmembrane Ligand Inhibits T Cell Receptor Activation, Yujie Ye Dec 2022

A Novel Transmembrane Ligand Inhibits T Cell Receptor Activation, Yujie Ye

Doctoral Dissertations

T lymphocytes (T cells) play essential roles in the adaptive immune system. Each mature T cell expresses one type of functional T cell receptor (TCR). The TCR recognizes antigens bound to the major histocompatibility complex (MHC) in antigen presenting cells. The resulting stimulation signal crosses the transmembrane domain of TCR and initiates downstream signaling cascades. The human immune system relies on TCRs to recognize a variety of pathogens. Normally, TCR can distinguish the self-antigens from pathogenic antigens. However, dysfunction or aberrant expression of TCRs causes different inflammatory and autoimmune diseases, which afflict millions of people annually (Chapter I). Current treatments …


Investigation Of Kinase Conformational Dynamics And Analytes Detection With Protein Nanopore, Fanjun Li Oct 2022

Investigation Of Kinase Conformational Dynamics And Analytes Detection With Protein Nanopore, Fanjun Li

Doctoral Dissertations

Protein nanopores are pore-forming proteins which have been developed as single-molecule biosensors. Due to the high sensitivity, selectivity, label-free and real-time detection methodology, protein nanopores have been used for a wide variety of applications. In this dissertation, we use ClyA nanopore to investigate kinase conformational dynamics and develop a kinase/nanopore system for the specific detection of kinase allosteric inhibitors. Besides, we engineer OmpG nanopore to be a sensor for nucleic acid detection. Protein kinases play essential roles in cellular regulation by catalyzing the phosphorylation of target proteins and are promising drug targets. The conformational dynamics are critical for kinase functions. …


Controlling Myosin’S Function Via Interactions Between The Substrate And The Active Site, Mike K. Woodward Sep 2022

Controlling Myosin’S Function Via Interactions Between The Substrate And The Active Site, Mike K. Woodward

Doctoral Dissertations

Molecular motors, such as myosin, have evolved to transduce chemical energy from ATP into mechanical work to drive essential cellular processes, from muscle contraction to vesicular transport. Dysfunction in these motors is a root cause of many pathologies necessitating the application of intrinsic control over molecular motor function. We hypothesized that altering the myosin’s energy substrate via minor positional changes to the triphosphate portion of the molecule will allow us to control the protein and affect its in vitro function. We utilized positional isomers of a synthetic non-nucleoside triphosphate, azobenzene triphosphate, and assessed whether myosin’s force- and motion-generating capacity could …


Investigating Structures And Functions Of Apoptotic Caspases, Ishankumar V. Soni Jun 2022

Investigating Structures And Functions Of Apoptotic Caspases, Ishankumar V. Soni

Doctoral Dissertations

Caspases are cysteine aspartate proteases involved in various cellular pathways including apoptosis, inflammation, and neurodegeneration. Caspase-9 is classified as an initiator apoptotic caspase that is activated upon intrinsic stress. Caspase-9 is composed of two domains: an N- terminal CARD domain and a catalytic core domain. We have employed hydrogen deuterium exchange mass spectrometry (H/DX-MS) to determine the 1) dynamics of the full-length caspase- 9, 2) dynamic impacts on caspase-9 upon substrate-induced dimerization, and 3) regions involved in the CARD: catalytic core domains interactions. Upon intrinsic stress, caspase-9 activates executioners, procaspase-3 and -7 but not procaspase-6. We have employed site-directed mutagenesis …


Crowd Control: Regulating The Spatial Organization Of Biopolymers And Gene Expression By Macromolecular Crowding, Gaurav Chauhan May 2022

Crowd Control: Regulating The Spatial Organization Of Biopolymers And Gene Expression By Macromolecular Crowding, Gaurav Chauhan

Doctoral Dissertations

The intracellular environment is crowded with macromolecules that can occupy a significant fraction of the cellular volume. This can give rise to attractive depletion interactions that impact the conformations and interactions of biopolymers, as well as their interactions with confining surfaces. We used computer simulations to study the effects of crowding on biologically-inspired models of polymers. We showed that crowding can lead to attractive interactions between two flexible ring polymers, and we further characterized the adsorption of both flexible and semiflexible polymers onto confining surfaces. These results indicate that crowding-induced depletion interactions could play a role in the spatial organization …


Improving The Biocompatibility Of The Bio-Inorganic Interface For Enhanced Photosystem I-Based Biophotovoltaic Device Performance, Alexandra H. Teodor May 2022

Improving The Biocompatibility Of The Bio-Inorganic Interface For Enhanced Photosystem I-Based Biophotovoltaic Device Performance, Alexandra H. Teodor

Doctoral Dissertations

The world’s energy demands are projected to increase by nearly 50% by the year 2040, and consumption of carbon-based fuels continues to release greenhouse gases such as carbon dioxide and methane into the atmosphere. This has been causally linked with climate change and increased extreme weather events, which has been further linked to adverse health outcomes and negative effects on biodiversity, food security, and increased disease transmission. Clearly, there is a need for a sustainable, carbon-free, and cost-effective method of energy production to meet growing energy production demands. The sun irradiates Earth’s surface annually with ~80,000 terawatts (TW), making solar …


Quantitative Imaging Of Tensile Forces At Cell-Cell Junction With Dna-Based Probes, Puspam Keshri Feb 2022

Quantitative Imaging Of Tensile Forces At Cell-Cell Junction With Dna-Based Probes, Puspam Keshri

Doctoral Dissertations

Mechanical forces are an integral part in biology, they regulate several cellular properties, such as morphology, proliferation, migration. These forces are also involved in receptor signaling and the differentiation of different cell types. Different proteins and biomolecules such as cadherin, integrin, notch proteins are essential elements of these processes. Measuring these intercellular forces are challenging considering the minimal intensity (piconewton-level) of these molecular forces. In our lab, we have developed a membrane DNA tension probe (MDTP) that uses a DNA hairpin module to sense tensile forces and has a lipid anchor to modify onto live-cell membranes. The programmability of DNA …


Understanding How Camkii Holoenzyme Dynamics Facilities Activation-Triggered Subunit Exchange, Ana P. Torres-Ocampo Oct 2021

Understanding How Camkii Holoenzyme Dynamics Facilities Activation-Triggered Subunit Exchange, Ana P. Torres-Ocampo

Doctoral Dissertations

Long-term memory and learning are still poorly understood from a molecular and cellular standpoint. Ca2+/calmodulin-dependent protein kinase II (CaMKII) is an oligomeric kinase that is involved in this remarkable process. However, the molecular details of its specific roles in these processes remains elusive. CaMKII activation-triggered subunit exchange presents a novel possible mechanism involved in long-term memory and learning by exchanging active subunits with other CaMKIIs. CaMKII subunit exchange also shows that exchanged CaMKIIs spread their phosphorylation state to newly synthesized CaMKIIs. This provides a long-lasting signal that might possibly be involved in long-term memory by escaping a cell’s …


Modulation Of Protein Dynamics By Ligand Binding And Solvent Composition, Richard J. Lindsay Aug 2021

Modulation Of Protein Dynamics By Ligand Binding And Solvent Composition, Richard J. Lindsay

Doctoral Dissertations

Many proteins undergo conformational switching in order to perform their cellular functions. A multitude of factors may shift the energy landscape and alter protein dynamics with varying effects on the conformations they explore. We apply atomistic molecular dynamics simulations to a variety of biomolecular systems in order to investigate how factors such as pressure, the chemical environment, and ligand binding at distant binding pockets affect the structure and dynamics of these protein systems. Further, we examine how such changes should be characterized. We first investigate how pressure and solvent modulate ligand access to the active site of a bacterial lipase …


Novel Approaches Towards Improved Purity In High Yield Transcription Reactions, Elvan Cavac Jun 2021

Novel Approaches Towards Improved Purity In High Yield Transcription Reactions, Elvan Cavac

Doctoral Dissertations

High yields of RNA (e.g., mRNA, gRNA, lncRNA) are routinely prepared following a two-step approach: high yield in vitro transcription using T7 RNA polymerase, followed by extensive purification using gel or chromatic methods. In high yield transcription reactions, as RNA accumulates in solution, T7 RNA polymerase rebinds and extends the encoded RNA (using the RNA as a template), resulting in a product pool contaminated with longer than desired, (partially) double stranded impurities. Current purification methods often fail to fully eliminate these impurities which, if present in therapeutics, can stimulate the innate immune response with potentially fatal consequences. This study establishes …


Synthetic Heterosynaptic Plasticity Enhances The Versatility Of Memristive Systems Emulating Bio-Synapse Structure And Function, William T. Mcclintic May 2021

Synthetic Heterosynaptic Plasticity Enhances The Versatility Of Memristive Systems Emulating Bio-Synapse Structure And Function, William T. Mcclintic

Doctoral Dissertations

Memristive systems occur in nature and are hallmarked via pinched hysteresis, the difference in the forward and reverse pathways for a given phenomenon. For example, neurons of the human brain are composed of synapses which apply the properties of memristance for neuronal communication, learning, and memory consolidation. Modern technology has much to gain from the characteristics of memristive systems, including lower power operation, on-chip memory, and bio-inspired computing. What is more, a relationship between memristive systems and synaptic plasticity exists and can be investigated focusing on homosynaptic and heterosynaptic plasticity. Where homosynaptic plasticity applies to interactions between neurons at a …


Critical Behavior In Evolutionary And Population Dynamics, Stephen Walter Ordway Jan 2021

Critical Behavior In Evolutionary And Population Dynamics, Stephen Walter Ordway

Doctoral Dissertations

“This study is an exploration of phase transition behavior in evolutionary and population dynamics, and techniques for predicting population changes, across the disciplines of physics, biology, and computer science. Under the looming threat of climate change, it is imperative to understand the dynamics of populations under environmental stress and to identify early warning signals of population decline. These issues are explored here in (1) a computational model of evolutionary dynamics, (2) an experimental system of decaying populations under environmental stress, and (3) a machine learning approach to predict population changes based on environmental factors. Through the lens of critical phase …


Controlled Membrane Remodeling By Nanospheres And Nanorods: Experiments Targeting The Design Principles For Membrane-Based Materials, Sarah Zuraw-Weston Dec 2020

Controlled Membrane Remodeling By Nanospheres And Nanorods: Experiments Targeting The Design Principles For Membrane-Based Materials, Sarah Zuraw-Weston

Doctoral Dissertations

In this thesis we explore two experimental systems probing the interactions of nanoparticles with lipid bilayer membranes. Inspired by the ability of cell membranes to alter their shape in response to bound particles, we report two experimental studies: one of nanospheres the other of long, slender nano-rods binding to lipid bilayer vesicles and altering the membrane shape. Our work illuminates the role of particle geometry, particle concentration, adhesion strength and membrane tension in how membrane morphology is determined. We combine giant unilamellar vesicles with oppositely charged nanoparticles, carefully tuning adhesion strength, membrane tension and particle concentration. In the case of …


Micro-Physiological Models To Mimic Mucosal Barrier Complexity Of The Human Intestine In Vitro, Abhinav Sharma Dec 2020

Micro-Physiological Models To Mimic Mucosal Barrier Complexity Of The Human Intestine In Vitro, Abhinav Sharma

Doctoral Dissertations

The mucosal barrier in the intestine is vital to maintain selective absorption of nutrients while protecting internal tissues and maintaining symbiotic relationship with luminal microbiota. This bio-barrier consists of a cellular epithelial barrier and an acellular mucus barrier. Secreted mucus regulates barrier function via in situ biochemical and biophysical interaction with luminal content that continually evolves during digestion and absorption. Increasing evidence suggests that a mucus barrier is indispensable to maintain homeostasis in the gastrointestinal tract. However, the importance of mucus barrier is largely underrated for in vitro mucosal tissue modeling. The major gap is the lack of experimental material …


Computer Simulations Of Biological Systems: From Protein Dynamics To Drug Discovery, Rupesh Agarwal Dec 2020

Computer Simulations Of Biological Systems: From Protein Dynamics To Drug Discovery, Rupesh Agarwal

Doctoral Dissertations

Computational biophysics methods such as molecular dynamics (MD) simulations are often used in combination with experimental techniques like neutron scattering, NMR, and FTIR to explore protein conformational landscapes. With the improvements in experimental techniques, there is also a need to continually optimize the MD forcefield parameters to make precise predictions that match experimental results. To complement many of these experiments, an accurate model of deuteration is frequently required, but has been elusive. In our work, we developed a novel method to capture isotope effects in classical MD simulations by re-parameterization of the bonded terms of the CHARMM forcefield using quantum …


Investigating Transmembrane-Lipid Interactions Of Epha2 And Ph Responsive Peptides, Katherine M. Stefanski Dec 2020

Investigating Transmembrane-Lipid Interactions Of Epha2 And Ph Responsive Peptides, Katherine M. Stefanski

Doctoral Dissertations

Single-pass membrane receptor signaling plays vital roles in human development and maintaining homeostasis. These membrane receptors can also have causative functions in several diseases including cancer. Much is known about the structure and signaling outcomes of these receptors but the mechanistic details of how they pass an extracellular signal across the membrane and into cytoplasm via the transmembrane (TM) domain is unclear. It is further unknown how or if interactions with membrane lipids facilitate and/or regulate these events. Here we use the TYPE7 peptide to target the TM region of a receptor tyrosine kinase, EphA2. EphA2 engages in both tumorigenic …


Characterization Of Β-2-Microglobulin Pre-Amyloid Oligomers And Their Role In Amyloid Inhibition, Tyler M. Marcinko Oct 2019

Characterization Of Β-2-Microglobulin Pre-Amyloid Oligomers And Their Role In Amyloid Inhibition, Tyler M. Marcinko

Doctoral Dissertations

In dialysis patients, β-2 microglobulin (β2m) can aggregate and eventually form amyloid fibrils in a condition known as dialysis-related amyloidosis, which deleteriously affects joint, bone, and organ function, and eventually causes organ failure. To understand the early stages of the amyloid assembly process, we have employed a series of biophysical tools including chromatography, spectroscopy, and most especially, native electrospray ionization (ESI) together with ion mobility mass spectrometry (IM-MS) to study soluble pre-amyloid oligomeric species. We have also collaborated and integrated computational modeling to help better understand and rationalize the structural basis behind oligomerization. Recently, several small molecules have been identified …


Rna-Seq And Mechanistic Enzymology Confirm Rna Self-Templated Extension By T7 Rna Polymerase And Suggest Novel Approaches Towards Improved In Vitro Rna Synthesis, Yasaman Gholamalipour Oct 2019

Rna-Seq And Mechanistic Enzymology Confirm Rna Self-Templated Extension By T7 Rna Polymerase And Suggest Novel Approaches Towards Improved In Vitro Rna Synthesis, Yasaman Gholamalipour

Doctoral Dissertations

Synthetic RNA is widely used in basic science, nanotechnology and therapeutics research. The vast majority of this RNA is synthesized in vitro by T7 RNA polymerase. However, the desired RNA is generally contaminated with products longer and shorter than the DNA-encoded product. To better understand these undesired byproducts and the processes that generate them, we analyzed in vitro transcription reactions using RNA-Seq as a tool. The results unambiguously confirmed that product RNA rebinds to the polymerase and self-primes (in cis) generation of a hairpin duplex, a process that favorably competes with promoter driven synthesis under high yield reaction conditions. …


Multiscale Simulations Of Intrinsically Disordered Proteins, Xiaorong Liu Jul 2019

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 …


Bio-Inspired Polymers That Bind And Deliver Protein Cargo, Nicholas D. Posey Mar 2019

Bio-Inspired Polymers That Bind And Deliver Protein Cargo, Nicholas D. Posey

Doctoral Dissertations

Delivering functional proteins and antibodies into cells can allow researchers to probe the intracellular environment, discover new cellular pathways, and pioneer new therapeutics. However, the entry of exogenous, charged molecules, like proteins, into the cell is usually restricted by the membrane, thereby hindering intracellular delivery. Membrane permeable molecules such as cell penetrating peptides (CPPs) and protein transduction domains (PTDs) can be used to bypass the cell membrane and deliver protein into the cell, but these peptides involve iterative and laborious syntheses and are limited in terms of their chemical diversity. This dissertation work overall focuses on the design and synthesis …


Probing Apoptotic Caspase Allostery And Exosite Interactions For Alternative Regulation, Derek J. Macpherson Mar 2019

Probing Apoptotic Caspase Allostery And Exosite Interactions For Alternative Regulation, Derek J. Macpherson

Doctoral Dissertations

Programmed cell death, or apoptosis is a critical homeostatic pathway that monitors the balance of cell life and death. Apoptosis is regulated by a class of enzymes known as the cysteine aspartic proteases, or the caspases. The 12 human caspases that play important roles in the progression and regulation of apoptosis and inflammation. Caspases are tightly regulated by numerous factors including enzymatic activation, post-translational modifications, metal ligand binding, and protein modulation. Aberrant caspase activation and regulation has been implicated in the progression of numerous diseases such as proliferative diseases and neurodegeneration. The deeply entwined nature of caspases and apoptosis makes …


Characterization Of The Motion Of Cellulose Synthase Protein Complexes In The Plant Cell Membrane, Nina Zehfroosh Mar 2019

Characterization Of The Motion Of Cellulose Synthase Protein Complexes In The Plant Cell Membrane, Nina Zehfroosh

Doctoral Dissertations

The polysaccharide cellulose is the main component of plant cell walls, so it is the most abundant polymer on Earth. While it is widely used in industry due to its remarkable properties, such as renewability and biodegradability, its biosynthesis is still not well understood. The large transmembrane protein Cellulose Synthase Complex (CSC) is responsible for synthesizing cellulose by polymerizing UDP glucose into the constituent glucan chains of cellulose. In this project, I used variable angle epi-fluorescence microscopy (VAEM) in combination with single-particle tracking to characterize the motion of GFP labeled CSCs in the hypocotyl of Arabidopsis thaliana (A. thaliana …


Characterization Of She1 Spindle Role Using Ceullular, Biochemical, And Biophysical Methods, Yili Zhu Jul 2018

Characterization Of She1 Spindle Role Using Ceullular, Biochemical, And Biophysical Methods, Yili Zhu

Doctoral Dissertations

During development, metaphase spindles undergo large movement and/or rotation to determine the cell division axis. While it has been shown that spindle translocation is achieved by astral microtubules pulling and/or pushing the cortex, how metaphase spindle stability is maintained during translocation remains not fully understood. In budding yeast, our lab has previously proposed a model for spindle orientation wherein the mitotic spindle protein She1 promotes spindle translocation across the bud neck by polarizing cortical dynein pulling activity on the astral microtubules. Intriguingly, She1 exhibits dominant spindle localization throughout the cell cycle. However, whether She1 has any additional role on the …


Studies On The P. Aeruginosa T3s Translocon Assembly: Interaction Of Popd With Membranes, Yuzhou Tang Jul 2018

Studies On The P. Aeruginosa T3s Translocon Assembly: Interaction Of Popd With Membranes, Yuzhou Tang

Doctoral Dissertations

Type III secretion (T3S) system is deployed by a wide range of pathogens to manipulate host cell response and establish infection. The T3S system is a syringe-like apparatus that spans across the double membrane of bacteria, protruding 50nm-80nm into the extracellular space and connecting with target cell membrane. In Pseudomonas aeruginosa, the proteins PopB and PopD are secreted and found associated with the target eukaryotic cell membrane. These two proteins are believed to form a transmembrane complex or translocon to allow effector protein translocation. Despite its key role in pathogenesis, the assembly mechanism and structure of this critical transmembrane …


Observing The Molecular Basis Of Thin Filament Activation With A Three Bead Laser Trap Assay, Thomas Longyear Mar 2018

Observing The Molecular Basis Of Thin Filament Activation With A Three Bead Laser Trap Assay, Thomas Longyear

Doctoral Dissertations

Muscle contracts after calcium (Ca++) is released into the muscle cell, resulting from a cascade of events which result in myosin, the molecular motor of muscle, to produce force and motion. Myosin cyclically binds to a regulated thin filament, using the chemical energy of ATP to produce force and motion. Perturbations in muscle, such as a build-up of metabolic by-products or point mutations in key contractile proteins, can inhibit these functions in both skeletal and cardiac muscle either acutely or chronically. Despite the many years we have studied skeletal and cardiac muscle, we still do not have a clear picture …


The Role Of The Metallochaperone Hypa In The Acid Survival And Activities Of Nickel Enzymes In Helicobacter Pylori, Heidi Hu Mar 2018

The Role Of The Metallochaperone Hypa In The Acid Survival And Activities Of Nickel Enzymes In Helicobacter Pylori, Heidi Hu

Doctoral Dissertations

Helicobacter pylori is a bacterium that has colonized the human gastric mucosa of over 50% of the world population. Persistent infection can cause gastritis, peptic ulcers, and cancers. The ability of H. pylori to colonize the acidic environment of the human stomach is dependent on the activity of the nickel containing enzymes, urease and NiFe-hydrogenase. The nickel metallochaperone, HypA, was previously shown to be required for the full activity of both enzymes. In addition to a Ni-binding site, HypA also contains a structural Zn site, which has been characterized to alter its averaged structure depending on pH and the presence …


Dissecting Molecular Pathways That Ensure Proper Chromosome Segregation And Cell Division, Anna Ye Nov 2017

Dissecting Molecular Pathways That Ensure Proper Chromosome Segregation And Cell Division, Anna Ye

Doctoral Dissertations

Equal segregation of the genome is a prerequisite for cell survival. During cell division the duplicated DNA is compacted into chromosomes and a multi-protein macrostructure, known as the kinetochore (Kt), is assembled on each copy of compacted DNA. Simultaneously, the mitotic spindle, which is made up of microtubules (MTs), is built to facilitate the equal distribution of the chromosomes between the resulting daughter cells. Kinetochores mediate the interaction between the MTs and the chromosomes, properly positioning them for segregation. To ensure that the DNA is equally divided in every cell division, cells have built a surveillance system to detect any …


Pore Forming Protein Assembly And The Use In Nanopore Sensing: A Study On E. Coli Proteins Clya And Ompg, Monifa Fahie Nov 2017

Pore Forming Protein Assembly And The Use In Nanopore Sensing: A Study On E. Coli Proteins Clya And Ompg, Monifa Fahie

Doctoral Dissertations

Pore forming proteins are typically the proteins that form channels in membranes. They have several roles ranging from molecule transport to triggering the death of a cell. This work focuses on two E. coli pore forming proteins that have vastly differing roles in nature. Outer membrane protein G (OmpG) is an innocuous β-barrel porin while Cytolysin A (ClyA) is an α-helical pore forming toxin. For OmpG we probed its potential to be a nanopore sensor for protein detection and quantification. A small high affinity ligand, biotin, was covalently attached to loop 6 of OmpG and used to capture biotin-binding proteins. …