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Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Assessing The Potential Impact Of Nanotechnology On The Purification Of Water, Noor Khan May 2019

Assessing The Potential Impact Of Nanotechnology On The Purification Of Water, Noor Khan

Quest

Independent Research Paper

Research in progress for PHYS 2426: University Physics II

Faculty Mentor: Raji Kannampuzha, Ph.D.

The following paper represents research work done by students in a University Physics 2426 class, the second half of a two-semester introductory course in physics. It is a calculus-based physics course, intended primarily for physics, chemistry, math, and engineering majors. Students are introduced to the concept of academic research by learning to ask research-focused questions and then use the library resources to pursue outside research to find answers. For this assignment, students are asked to investigate a physical science, biological science, or ...


Activities And Classroom Demonstrations In Biological Physics: A Resource Document, Philip C. Nelson, William Berner Jul 2018

Activities And Classroom Demonstrations In Biological Physics: A Resource Document, Philip C. Nelson, William Berner

Department of Physics Papers

We give detailed recipes for a number of classroom demonstrations relevant to biological physics instruction. We developed them mainly for use in 2nd-3rd year undergraduate Physics courses. But you can (and we do) use them for primary school, through high school, up to PhD candidates. You adapt the words for each audience, but a phenomenon is a phenomenon.

We also outline a 1-hour introduction to Python for undergraduate scientific computing.

Finally we document some outcomes from courses taught at U Pennsylvania using these resources and others cited here. This material was presented at a workshop at the AAPT meeting in ...


Structure And Mechanism Of Mycobacterial Topoisomerase I, Nan Cao May 2018

Structure And Mechanism Of Mycobacterial Topoisomerase I, Nan Cao

FIU Electronic Theses and Dissertations

The enzyme DNA topoisomerase I is an essential enzyme that plays an important role in eukaryotic and prokaryotic cellular processes such as DNA replication, transcription, recombination and repair. Mycobacterium tuberculosistopoisomerase I (MtTOP1) is a validated drug target for antituberculosis treatment. Mycobacterial topoisomerase I regulates the topological constraints in chromosomes and helps in maintaining the growth of mycobacteria. The N- terminal domain (NTD) of mycobacterial topoisomerase I contains conserved catalytic domains that along with the active site Tyrosine are involved in cleaving and rejoining a single strand of DNA. Magnesium is required in DNA cleavage activity of type IA topoisomerases ...


Heterochromatin Drives Organization Of Conventional And Inverted Nuclei, Martin Falk, Yana Feodorova, Natasha Naumova, Massachusetts Institute Of Technology, Illumina Incorporated, Heinrich Leonhardt, Ludwig Maximilians Universitat, Munchen, Job Dekker, University Of California, San Francisco Jan 2018

Heterochromatin Drives Organization Of Conventional And Inverted Nuclei, Martin Falk, Yana Feodorova, Natasha Naumova, Massachusetts Institute Of Technology, Illumina Incorporated, Heinrich Leonhardt, Ludwig Maximilians Universitat, Munchen, Job Dekker, University Of California, San Francisco

University of Massachusetts Medical School Faculty Publications

The mammalian cell nucleus displays a remarkable spatial segregation of active euchromatic from inactive heterochromatic genomic regions. In conventional nuclei, euchromatin is localized in the nuclear interior and heterochromatin at the nuclear periphery. In contrast, rod photoreceptors in nocturnal mammals have inverted nuclei, with a dense heterochromatic core and a thin euchromatic outer shell. This inverted architecture likely converts rod nuclei into microlenses to facilitate nocturnal vision, and may relate to the absence of particular proteins that tether heterochromatin to the lamina. However, both the mechanism of inversion and the role of interactions between different types of chromatin and the ...


Learning From Disorder And Noise In Physical Biology, Taylor Emil Firman Jan 2018

Learning From Disorder And Noise In Physical Biology, Taylor Emil Firman

Electronic Theses and Dissertations

Stochasticity, disorder, and noise play crucial roles in the functioning of many biological systems over many different length scales. On the molecular scale, most proteins are envisioned as pristinely folded structures, but intrinsically disordered proteins (IDPs) have no such folded state and still serve distinct purposes within the cell. At the scale of gene regulation, realistic in vivo conditions produce stochastic fluctuations in gene expression that can lead to advantageous bet-hedging strategies, but can be difficult to characterize using a deterministic framework. Even at the organismal scale, germband extension (GBE) in Drosophila melanogaster embryos systematically elongates the epithelial tissue using ...


The Complex Role Of Sequence And Structure In The Stability And Function Of The Tim Barrel Proteins, Yvonne H. Chan Nov 2017

The Complex Role Of Sequence And Structure In The Stability And Function Of The Tim Barrel Proteins, Yvonne H. Chan

GSBS Dissertations and Theses

Sequence divergence of orthologous proteins enables adaptation to a plethora of environmental stresses and promotes evolution of novel functions. As one of the most common motifs in biology capable of diverse enzymatic functions, the TIM barrel represents an ideal model system for mapping the phenotypic manifestations of protein sequence. Limits on evolution imposed by constraints on sequence and structure were investigated using a model TIM barrel protein, indole-3-glycerol phosphate synthase (IGPS). Exploration of fitness landscapes of phylogenetically distant orthologs provides a strategy for elucidating the complex interrelationship in the context of a protein fold.

Fitness effects of point mutations in ...


Fluorescence Polarization Control For On-Off Switching Of Single Molecules At Cryogenic Temperatures, Christiaan Hulleman, Maximiliaan Huisman, Robert Moerland, David Grünwald, Sjoerd Stallinga, Bernd Rieger Oct 2017

Fluorescence Polarization Control For On-Off Switching Of Single Molecules At Cryogenic Temperatures, Christiaan Hulleman, Maximiliaan Huisman, Robert Moerland, David Grünwald, Sjoerd Stallinga, Bernd Rieger

University of Massachusetts Medical School Faculty Publications

Light microscopy allowing sub-diffraction limited resolution has been among the fastest developing techniques at the interface of biology, chemistry and physics. Intriguingly no theoretical limit exists on how far the underlying measurement uncertainty can be lowered. In particular data fusion of large amounts of images can reduce the measurement error to match the resolution of structural methods like cryo-electron microscopy. Fluorescence, although reliant on a reporter molecule and therefore not the first choice to obtain ultra resolution structures, brings highly specific labeling of molecules in a large assemble to the table and inherently allows the detection of multiple colors, which ...


Structure Of Rna Polymerase Bound To Ribosomal 30s Subunit, Gabriel Demo, Aviram Rasouly, Nikita Vasilyev, Vladimir Svetlov, Anna B. Loveland, Ruben Diaz-Avalos, Nikolaus Grigorieff, Evgeny Nudler, Andrei A. Korostelev Oct 2017

Structure Of Rna Polymerase Bound To Ribosomal 30s Subunit, Gabriel Demo, Aviram Rasouly, Nikita Vasilyev, Vladimir Svetlov, Anna B. Loveland, Ruben Diaz-Avalos, Nikolaus Grigorieff, Evgeny Nudler, Andrei A. Korostelev

Open Access Articles

In bacteria, mRNA transcription and translation are coupled to coordinate optimal gene expression and maintain genome stability. Coupling is thought to involve direct interactions between RNA polymerase (RNAP) and the translational machinery. We present cryo-EM structures of E. coli RNAP core bound to the small ribosomal 30S subunit. The complex is stable under cell-like ionic conditions, consistent with functional interaction between RNAP and the 30S subunit. The RNA exit tunnel of RNAP aligns with the Shine-Dalgarno-binding site of the 30S subunit. Ribosomal protein S1 forms a wall of the tunnel between RNAP and the 30S subunit, consistent with its role ...


Fret-Based Investigations Of The Structure-Function Relationships In The Nmda Receptor, Drew M. Dolino May 2017

Fret-Based Investigations Of The Structure-Function Relationships In The Nmda Receptor, Drew M. Dolino

UT GSBS Dissertations and Theses (Open Access)

The N-methyl-D-aspartate (NMDA) receptor is one member of a class of proteins known as the ionotropic glutamate receptors. Ionotropic glutamate receptors mediate the majority of excitatory neurotransmission in the central nervous system, with the NMDA receptor standing out among these receptors for its requirement of a co-agonist, its magnesium-block-based coincidence detection, its slow kinetics, its calcium permeability, its allosteric modulation, and its especially important functional roles in synaptic plasticity, excitotoxicity, and more. In recent years, a wealth of structural information has come about describing endpoint structures to high resolution, but such structures are unable to fully resolve the movements ...


Mechanism Of Ribosome Rescue By Arfa And Rf2, Gabriel Demo, Egor Svidritskiy, Rohini Madireddy, Ruben Diaz-Avalos, Timothy Grant, Nikolaus Grigorieff, Duncan Sousa, Andrei A. Korostelev Mar 2017

Mechanism Of Ribosome Rescue By Arfa And Rf2, Gabriel Demo, Egor Svidritskiy, Rohini Madireddy, Ruben Diaz-Avalos, Timothy Grant, Nikolaus Grigorieff, Duncan Sousa, Andrei A. Korostelev

Open Access Articles

ArfA rescues ribosomes stalled on truncated mRNAs by recruiting release factor RF2, which normally binds stop codons to catalyze peptide release. We report two 3.2 A resolution cryo-EM structures - determined from a single sample - of the 70S ribosome with ArfA*RF2 in the A site. In both states, the ArfA C-terminus occupies the mRNA tunnel downstream of the A site. One state contains a compact inactive RF2 conformation. Ordering of the ArfA N-terminus in the second state rearranges RF2 into an extended conformation that docks the catalytic GGQ motif into the peptidyl-transferase center. Our work thus reveals the structural ...


Improving The Usage Of Unnatural Amino Acids In Proteins: Thioamides And Other Biophysical Probes, Christopher Russell Walters Jan 2017

Improving The Usage Of Unnatural Amino Acids In Proteins: Thioamides And Other Biophysical Probes, Christopher Russell Walters

Publicly Accessible Penn Dissertations

Methods for genetically and synthetically manipulating protein composition enable a greater flexibility in the study of protein dynamics and function. However, current techniques for incorporating biophysical probes in the form of unnatural amino acids (Uaas) can suffer from poor yield, limited selectivity for the desired probe, and an insufficient understanding of the impact that the probe has on protein structure and function. Each of the studies discussed herein addresses one or more of these shortcomings in an effort to improve the usage of Uaas in biochemistry. We have shown that using inteins as traceless, cleavable purification tags enables the separation ...


Identifying The Relevance Of C-Reactive Protein Conformers And The Advancement Of A Membrane Curvature Binding Assay, Carrie Leine Moon Jan 2017

Identifying The Relevance Of C-Reactive Protein Conformers And The Advancement Of A Membrane Curvature Binding Assay, Carrie Leine Moon

Electronic Theses and Dissertations

Lipid membranes play a vital role in cell signaling processes. Membrane shape and lipid content affect interactions between cellular membranes and proteins. This research focuses on characterizing those interactions and their impact by using various biochemical and biophysical assays. These assays were applied to C-reactive protein (CRP), an immune system protein that interacts with lipid membranes and has at least two forms with different properties. Native, pentameric CRP (pCRP) is found in blood serum and is commonly used as a marker for inflammation. The modified form of CRP (mCRP) binds to the protein C1q, which activates the complement immune response ...


Symmetry And Reconstruction Of Particle Structure From Random Angle Diffraction Patterns, Sandi Wibowo Dec 2016

Symmetry And Reconstruction Of Particle Structure From Random Angle Diffraction Patterns, Sandi Wibowo

Theses and Dissertations

The problem of determining the structure of a biomolecule, when all the evidence from experiment consists of individual diffraction patterns from random particle orientations, is the central theoretical problem with an XFEL. One of the methods proposed is a calculation over all measured diffraction patterns of the average angular correlations between pairs of points on the diffraction patterns. It is possible to construct from these a matrix B characterized by angular momentum quantum number l, and whose elements are characterized by radii q and q’ of the resolution shells. If matrix B is considered as dot product of vectors, which ...


The Mammalian Linc Complex Regulates Genome Transcriptional Responses To Substrate Rigidity, Samer G. Alam, Qiao Zhang, Nripesh Prasad, Yuan Li, Srikar Chamala, Ram Kuchibhotla, Birendra Kc, Varun Aggarwal, Shristi Shrestha, Angela L. Jones, Shawn E. Levy, Kyle J. Roux, Jeffrey A. Nickerson, Tanmay P. Lele Dec 2016

The Mammalian Linc Complex Regulates Genome Transcriptional Responses To Substrate Rigidity, Samer G. Alam, Qiao Zhang, Nripesh Prasad, Yuan Li, Srikar Chamala, Ram Kuchibhotla, Birendra Kc, Varun Aggarwal, Shristi Shrestha, Angela L. Jones, Shawn E. Levy, Kyle J. Roux, Jeffrey A. Nickerson, Tanmay P. Lele

Open Access Articles

Mechanical integration of the nucleus with the extracellular matrix (ECM) is established by linkage between the cytoskeleton and the nucleus. This integration is hypothesized to mediate sensing of ECM rigidity, but parsing the function of nucleus-cytoskeleton linkage from other mechanisms has remained a central challenge. Here we took advantage of the fact that the LINC (linker of nucleoskeleton and cytoskeleton) complex is a known molecular linker of the nucleus to the cytoskeleton, and asked how it regulates the sensitivity of genome-wide transcription to substratum rigidity. We show that gene mechanosensitivity is preserved after LINC disruption, but reversed in direction. Combined ...


Microfluidic Cantilever Detects Bacteria And Measures Their Susceptibility To Antibiotics In Small Confined Volumes, Hashem Etayash, M. F. Khan, Kamaljit Kaur, Thomas Thundat Oct 2016

Microfluidic Cantilever Detects Bacteria And Measures Their Susceptibility To Antibiotics In Small Confined Volumes, Hashem Etayash, M. F. Khan, Kamaljit Kaur, Thomas Thundat

Pharmacy Faculty Articles and Research

In the fight against drug-resistant bacteria, accurate and high-throughput detection is essential. Here, a bimaterial microcantilever with an embedded microfluidic channel with internal surfaces chemically or physically functionalized with receptors selectively captures the bacteria passing through the channel. Bacterial adsorption inside the cantilever results in changes in the resonance frequency (mass) and cantilever deflection (adsorption stress). The excitation of trapped bacteria using infrared radiation (IR) causes the cantilever to deflect in proportion to the infrared absorption of the bacteria, providing a nanomechanical infrared spectrum for selective identification. We demonstrate the in situ detection and discrimination of Listeria monocytogenes at a ...


Ribosome*Rela Structures Reveal The Mechanism Of Stringent Response Activation, Anna B. Loveland, Eugene Bah, Rohini Madireddy, Ying Zhang, Axel F. Brilot, Nikolaus Grigorieff, Andrei A. Korostelev Jul 2016

Ribosome*Rela Structures Reveal The Mechanism Of Stringent Response Activation, Anna B. Loveland, Eugene Bah, Rohini Madireddy, Ying Zhang, Axel F. Brilot, Nikolaus Grigorieff, Andrei A. Korostelev

Open Access Articles

Stringent response is a conserved bacterial stress response underlying virulence and antibiotic resistance. RelA/SpoT-homolog proteins synthesize transcriptional modulators (p)ppGpp, allowing bacteria to adapt to stress. RelA is activated during amino-acid starvation, when cognate deacyl-tRNA binds to the ribosomal A (aminoacyl-tRNA) site. We report four cryo-EM structures of E. coli RelA bound to the 70S ribosome, in the absence and presence of deacyl-tRNA accommodating in the 30S A site. The boomerang-shaped RelA with a wingspan of more than 100 A wraps around the A/R (30S A-site/RelA-bound) tRNA. The CCA end of the A/R tRNA pins the ...


Closing The Net On Retroviruses, Jeremy Luban Jul 2016

Closing The Net On Retroviruses, Jeremy Luban

Open Access Articles

Structural studies reveal how an antiviral factor forms a molecular net to restrict retroviruses including HIV-1.


Single Molecule Analysis Reveals Reversible And Irreversible Steps During Spliceosome Activation, Aaron A. Hoskins, Margaret L. Rodgers, Larry J. Friedman, Jeff Gelles, Melissa J. Moore May 2016

Single Molecule Analysis Reveals Reversible And Irreversible Steps During Spliceosome Activation, Aaron A. Hoskins, Margaret L. Rodgers, Larry J. Friedman, Jeff Gelles, Melissa J. Moore

Open Access Articles

The spliceosome is a complex machine composed of small nuclear ribonucleoproteins (snRNPs) and accessory proteins that excises introns from pre-mRNAs. After assembly the spliceosome is activated for catalysis by rearrangement of subunits to form an active site. How this rearrangement is coordinated is not well-understood. During activation, U4 must be released to allow U6 conformational change, while Prp19 complex (NTC) recruitment is essential for stabilizing the active site. We used multi-wavelength colocalization single molecule spectroscopy to directly observe the key events in Saccharomyces cerevisiae spliceosome activation. Following binding of the U4/U6.U5 tri-snRNP, the spliceosome either reverses assembly by ...


Ensemble Cryo-Em Uncovers Inchworm-Like Translocation Of A Viral Ires Through The Ribosome, Priyanka D. Abeyrathne, Cha San Koh, Timothy Grant, Nikolaus Grigorieff, Andrei A. Korostelev May 2016

Ensemble Cryo-Em Uncovers Inchworm-Like Translocation Of A Viral Ires Through The Ribosome, Priyanka D. Abeyrathne, Cha San Koh, Timothy Grant, Nikolaus Grigorieff, Andrei A. Korostelev

Open Access Articles

Internal ribosome entry sites (IRESs) mediate cap-independent translation of viral mRNAs. Using electron cryo-microscopy of a single specimen, we present five ribosome structures formed with the Taura syndrome virus IRES and translocase eEF2*GTP bound with sordarin. The structures suggest a trajectory of IRES translocation, required for translation initiation, and provide an unprecedented view of eEF2 dynamics. The IRES rearranges from extended to bent to extended conformations. This inchworm-like movement is coupled with ribosomal inter-subunit rotation and 40S head swivel. eEF2, attached to the 60S subunit, slides along the rotating 40S subunit to enter the A site. Its diphthamide-bearing tip ...


Stability Of Norwalk Virus Capsid Protein Interfaces Evaluated By In Silico Nanoindentation, Prakhar Bansal May 2016

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 ...


Determination Of Ubiquitin Fitness Landscapes Under Different Chemical Stresses In A Classroom Setting, David Mavor, Benjamin P. Roscoe, Daniel N. Bolon, James S. Fraser Apr 2016

Determination Of Ubiquitin Fitness Landscapes Under Different Chemical Stresses In A Classroom Setting, David Mavor, Benjamin P. Roscoe, Daniel N. Bolon, James S. Fraser

Open Access Articles

Ubiquitin is essential for eukaryotic life and varies in only 3 amino acid positions between yeast and humans. However, recent deep sequencing studies indicate that ubiquitin is highly tolerant to single mutations. We hypothesized that this tolerance would be reduced by chemically induced physiologic perturbations. To test this hypothesis, a class of first year UCSF graduate students employed deep mutational scanning to determine the fitness landscape of all possible single residue mutations in the presence of five different small molecule perturbations. These perturbations uncover 'shared sensitized positions' localized to areas around the hydrophobic patch and the C-terminus. In addition, we ...


Contributions Of Sequence And Structure To Ligand Selectivity In Class Ii Cobalamin Riboswitches, Samantha M. Webster Jan 2016

Contributions Of Sequence And Structure To Ligand Selectivity In Class Ii Cobalamin Riboswitches, Samantha M. Webster

Undergraduate Honors Theses

Riboswitches are gene regulatory elements found in the 5’-untranslated region of many bacterial genes. The direct binding of small molecule ligands induces conformational changes in the RNA that influence downstream expression machinery and determine the transcription or translation of an attached gene. Cobalamin riboswitches, which bind coenzyme-B12 and other cobalamin variants, are divided into two distinct classes. Cbl-I riboswitches contain a large peripheral element that limits riboswitch binding to only coenzyme-B12 (adenosylcobalamin, or AdoCbl). Cbl-II riboswitches do not contain the same peripheral element, and were originally thought to only bind smaller species of cobalamin (including methylcobalamin, or ...


X-Ray Characterization Of Mesophases And Phase Transitions Of Dna Analogues In Solutions, Mustafa Selcuk Yasar Jan 2016

X-Ray Characterization Of Mesophases And Phase Transitions Of Dna Analogues In Solutions, Mustafa Selcuk Yasar

Doctoral Dissertations

We think of DNA as double-stranded helices (duplex), but the polymer exists in many conformations. Several triplex and quadruplex DNA structures can be formed in laboratory settings and exist in nature. This thesis first provides a brief description of the nature of the order in arrays of duplex DNA under biologically relevant molecular crowding conditions. Then we compare the duplex DNA mesophases with the corresponding liquid crystalline phase behavior of the triplex and quadruplex DNA analogues. In particular, we focus on G-quadruplexes.

Observed in the folds of guanine-rich oligonucleotides, G-quadruplex structures are based on G-quartets formed by hydrogen bonding and ...


A 4d View On Mrna, Carlas Smith, Li-Chun Tu, David Grünwald Dec 2015

A 4d View On Mrna, Carlas Smith, Li-Chun Tu, David Grünwald

David Grünwald

Imaging single molecules in live cells in 4+ D (space, time and colors) is crucial for studying various biological processes, especially for observing the behavior of RNA molecules within the nuclear landscape [1]. RNA molecules are known to serve a multitude of tasks such as being templates for protein translation or to act as enzymes for regulating countless reactions in the nucleus [1]. Studying RNA kinetics in living cells can provide new information on RNA function or even human diseases, for instance caused by viruses such as the human immunodeficiency virus (HIV) [2]. A challenge to imaging nuclear RNA function ...


A 4d View On Mrna, Carlas Smith, Li-Chun Tu, David Grünwald Oct 2015

A 4d View On Mrna, Carlas Smith, Li-Chun Tu, David Grünwald

Open Access Articles

Imaging single molecules in live cells in 4+ D (space, time and colors) is crucial for studying various biological processes, especially for observing the behavior of RNA molecules within the nuclear landscape [1]. RNA molecules are known to serve a multitude of tasks such as being templates for protein translation or to act as enzymes for regulating countless reactions in the nucleus [1]. Studying RNA kinetics in living cells can provide new information on RNA function or even human diseases, for instance caused by viruses such as the human immunodeficiency virus (HIV) [2]. A challenge to imaging nuclear RNA function ...


Allosteric Inhibition Of A Stem Cell Rna-Binding Protein By An Intermediary Metabolite, Carina Clingman, Laura Deveau, Samantha Hay, Ryan Genga, Shivender Shandilya, Francesca Massi, Sean Ryder Sep 2015

Allosteric Inhibition Of A Stem Cell Rna-Binding Protein By An Intermediary Metabolite, Carina Clingman, Laura Deveau, Samantha Hay, Ryan Genga, Shivender Shandilya, Francesca Massi, Sean Ryder

Sean P. Ryder

Gene expression and metabolism are coupled at numerous levels. Cells must sense and respond to nutrients in their environment, and specialized cells must synthesize metabolic products required for their function. Pluripotent stem cells have the ability to differentiate into a wide variety of specialized cells. How metabolic state contributes to stem cell differentiation is not understood. In this study, we show that RNA-binding by the stem cell translation regulator Musashi-1 (MSI1) is allosterically inhibited by 18-22 carbon omega-9 monounsaturated fatty acids. The fatty acid binds to the N-terminal RNA Recognition Motif (RRM) and induces a conformational change that prevents RNA ...


An Investigation Of The Molecular And Biophysical Properties Of Metastatic Cells, Jones Trevor Nauseef May 2015

An Investigation Of The Molecular And Biophysical Properties Of Metastatic Cells, Jones Trevor Nauseef

Theses and Dissertations

Prostate cancer presents a significant paradox: it is very common, yet rarely fatal. To wit, the prostate is the most common non-skin tissue for cancer diagnosis in men in the United States. Despite its high incidence, fatal malignancy occurs in only a small fraction of diagnosed men. The fatal cases are characteristically defined by distant spread in the body, also known as metastasis. In order to metastasize a cancer cell must complete several sequential steps. These include degradation of and invasion through the epithelial basement membrane, typically through the loss of static intracellular adhesions with fellow epithelial cells; entrance into ...


Statistical Biophysics Blog: A Hello: The Point Of This Blog, Daniel M. Zuckerman Apr 2015

Statistical Biophysics Blog: A Hello: The Point Of This Blog, Daniel M. Zuckerman

Scholar Archive

No abstract provided.


Sucralose Destabilization Of Protein Structure, Lee Chen, Nimesh Shukla, Inha Cho, Erin F. Cohn, Erika A. Taylor, Christina M. Othon Mar 2015

Sucralose Destabilization Of Protein Structure, Lee Chen, Nimesh Shukla, Inha Cho, Erin F. Cohn, Erika A. Taylor, Christina M. Othon

Erika A. Taylor, Ph.D.

Sucralose is a commonly employed artificial sweetener that behaves very differently than its natural disaccharide counterpart, sucrose, in terms of its interaction with biomolecules. The presence of sucralose in solution is found to destabilize the native structure of two model protein systems: the globular protein bovine serum albumin and an enzyme staphylococcal nuclease. The melting temperature of these proteins decreases as a linear function of sucralose concentration. We correlate this destabilization to the increased polarity of the molecule. The strongly polar nature is manifested as a large dielectric friction exerted on the excited-state rotational diffusion of tryptophan using time-resolved fluorescence ...


De Novo Design And Engineering Of Functional Metal And Porphyrin-Binding Protein Domains, Bernard Howard Everson Feb 2015

De Novo Design And Engineering Of Functional Metal And Porphyrin-Binding Protein Domains, Bernard Howard Everson

All Dissertations, Theses, and Capstone Projects

In this work, I describe an approach to the rational, iterative design and characterization of two functional cofactor-binding protein domains. First, a hybrid computational/experimental method was developed with the aim of algorithmically generating a suite of porphyrin-binding protein sequences with minimal mutual sequence information. This method was explored by generating libraries of sequences, which were then expressed and evaluated for function. One successful sequence is shown to bind a variety of porphyrin-like cofactors, and exhibits light- activated electron transfer in mixed hemin:chlorin e6 and hemin:Zn(II)-protoporphyrin IX complexes. These results imply that many sophisticated functions such ...