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Articles 1 - 17 of 17

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

Investigation Of The Peptide-Lipid Interactions Of A Beta-Hairpin Antimicrobial Peptide Using Solid-State Nmr, Rajeswari Mani Jan 2007

Investigation Of The Peptide-Lipid Interactions Of A Beta-Hairpin Antimicrobial Peptide Using Solid-State Nmr, Rajeswari Mani

Retrospective Theses and Dissertations

Solid-state NMR (SSNMR) has gained importance as a versatile tool to elucidate the structure and function of many chemical and biological molecules. In this thesis, we have used SSNMR to study the interactions of an antimicrobial peptide (AMP), Protegrin-1 (PG-1) with membranes of varying lipid composition. Based on our studies we have proposed a model for the mechanism of action of PG-1 with two different lipid membranes. PG-1 is a disulfide-linked beta-sheet peptide with broad-spectrum antimicrobial activities. Similar to many AMPs, it selectively disrupts the anionic membranes of microbial cells but leaves the cholesterol-rich zwitterionic mammalian cell membranes intact.;Studying ...


Advanced Detection And Separation Methods: Developments In Surface-Enhanced Raman Scattering Readout Immunoassays And Electrochemically Modulated Liquid Chromatography, Betsy Jean Yakes Jan 2007

Advanced Detection And Separation Methods: Developments In Surface-Enhanced Raman Scattering Readout Immunoassays And Electrochemically Modulated Liquid Chromatography, Betsy Jean Yakes

Retrospective Theses and Dissertations

This dissertation explores the use of novel detection methods for biological and chemical components commonly found in the environment. It encompasses two techniques: surface-enhanced Raman scattering (SERS) and electrochemically modulated liquid chromatography (EMLC).;Immunoassays using SERS as a readout tool have been developed in this laboratory and have shown low levels of detection (i.e., pico- to femtomolar and single binding event detection) for disease and biowarfare agents. This thesis seeks to further the performance of this platform for bacteria detection and explore strategies to increase the SERS response. Specifically, the first section of this dissertation focuses on the detection ...


Subunits Of Highly Fluorescent Protein R-Phycoerythrin As Probes For Cell Imaging And Single-Molecule Detection , Dragan Isailovic Jan 2005

Subunits Of Highly Fluorescent Protein R-Phycoerythrin As Probes For Cell Imaging And Single-Molecule Detection , Dragan Isailovic

Retrospective Theses and Dissertations

R-phycoerythrin (R-PE) subunits and enzymatic digests were characterized by high-performance liquid chromatography (HPLC), capillary and gel electrophoresis, and HPLC-electrospray ionization mass spectrometry. Subunits were isolated from R-PE by HPLC and detected as single molecules by total internal reflection fluorescence microscopy (TIRFM). Favorable spectroscopic characteristics of R-PE subunits and digest peptides in the visible region of spectrum originate from phycoerythrobilin (PEB) and phycourobilin (PUB) chromophores. High absorption coefficients and fluorescence (even under denaturing conditions), broad excitation and emission fluorescence spectra, and low molecular weights make these molecules suitable for fluorescence labeling of biomolecules and cells.;Fluorescent proteins were further formed both ...


Real-Time Monitoring And Manipulation Of Single Bio-Molecules In Free Solution , Hung-Wing Li Jan 2005

Real-Time Monitoring And Manipulation Of Single Bio-Molecules In Free Solution , Hung-Wing Li

Retrospective Theses and Dissertations

The observation and manipulation of single biomolecules allow their dynamic behaviors to be studied to provide insight into molecular genetics, biochip assembly, biosensor design, DNA biophysics.;In a PDMS/glass microchannel, a nonuniform electroosmotic flow (EOF) was created. By using a scanning confocal fluorescence microscope and total internal-reflection fluorescence microscope (TIRFM), we demonstrated that negatively charged DNA molecules were focused by the nonuniform EOF into a thin layer at the glass surface. This phenomenon was applied to selectively detect target DNA molecules without requiring the separation of excessive probes and can be applied continuously to achieve high throughput.;A variable-angle-TIRFM ...


Molecular And Chemical Characterization Of Genes Involved In Maize Cuticular Wax Biosynthesis , M. Ann D. N. Perera Jan 2005

Molecular And Chemical Characterization Of Genes Involved In Maize Cuticular Wax Biosynthesis , M. Ann D. N. Perera

Retrospective Theses and Dissertations

The primary surfaces of the arial parts of plants, and the surfaces of reproductive organs are covered by an extra cellular layer called the cuticle. The cuticle provides the foremost protection to the plant in order to adapt to the terrestrial environment. The cuticle composed of a biopolymer (cutin), which is embedded in a coating of cuticular waxes. Understanding the biochemical, genetic and physiological mechanisms for the biosynthesis of these cuticular waxes is relatively poor. This body of work has established methods for the chemical analysis of the cuticular waxes of maize plants. I have used these methods to chemically ...


Mesoporous Silica Nanomaterials For Applications In Catalysis, Sensing, Drug Delivery And Gene Transfection , Daniela Rodica Radu Jan 2004

Mesoporous Silica Nanomaterials For Applications In Catalysis, Sensing, Drug Delivery And Gene Transfection , Daniela Rodica Radu

Retrospective Theses and Dissertations

The central theme of this dissertation is represented by the versatility of mesoporous silica nanomaterials in various applications such as catalysis and bio-applications, with main focus on biological applications of Mesoporous Silica Nanospheres (MSN). The metamorphosis that we impose to these materials from catalysis to sensing and to drug and gene delivery is detailed in this dissertation. First, we developed a synthetic method that can fine tune the amount of chemically accessible organic functional groups on the pores surface of MSN by exploiting electrostatic and size matching between the cationic alkylammonium head group of the CTAB surfactant and various anionic ...


Nonphotochemical Hole-Burning Imaging Studies Of In Vitro Carcinoma And Normal Cells Utilizing A Mitochondrial Specific Dye , Richard Joseph Walsh Jan 2002

Nonphotochemical Hole-Burning Imaging Studies Of In Vitro Carcinoma And Normal Cells Utilizing A Mitochondrial Specific Dye , Richard Joseph Walsh

Retrospective Theses and Dissertations

Low temperature Nonphotochemical Hole Burning (NPHB) Spectroscopy of the dye rhodamine 800 (MF680) was applied for the purpose of discerning differences between cultured normal and carcinoma ovarian surface epithelial (OSE) cells. Both the cell lines were developed and characterized at the Mayo Clinic (Rochester, MN), with the normal cell line having been transfected with a strain of temperature sensitive Simian Virus 40 Large T Antigen (SV40) for the purpose of extending the life of the cell culture without inducing permanent changes in the characteristics of the cell line. The cationic lipophilic fluorophore rhodamine 800 preferentially locates in in situ mitochondria ...


Analytical Chemistry At The Interface Between Materials Science And Biology , Janese Christine O'Brien Jan 2000

Analytical Chemistry At The Interface Between Materials Science And Biology , Janese Christine O'Brien

Retrospective Theses and Dissertations

This work describes several research efforts that lie at the new interfaces between analytical chemistry and other disciplines, namely materials science and biology. In the materials science realm, the search for new materials that may have useful or unique chromatographic properties motivated the synthesis and characterization of electrically conductive sol-gels. In the biology realm, the search for new surface fabrication schemes that would permit or even improve the detection of specific biological reactions motivated the design of miniaturized biological arrays. Collectively, this work represents some of analytical chemistry's newest forays into these disciplines;This dissertation is divided into six ...


Inductively Coupled Plasma Mass Spectrometry For Stable Isotope Metabolic Tracer Studies Of Living Systems , Elise Tuy Luong Jan 1999

Inductively Coupled Plasma Mass Spectrometry For Stable Isotope Metabolic Tracer Studies Of Living Systems , Elise Tuy Luong

Retrospective Theses and Dissertations

Sub-nanogram per gram levels of molybdenum (Mo) from human blood plasma are isolated by the use of anion exchange alumina microcolumns. Million-fold more concentrated spectral and matrix interferences such as sodium, chloride, sulfate, phosphate, etc. in the blood constituents are removed from the analyte. The recovery of Mo from the alumina column is 82 +/- 5% (n = 5). Isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS) is utilized for the quantitative ultra-trace concentration determination of Mo in bovine and human blood samples. The average Mo concentration in reference bovine serum determined by our method is 10.2 +/- 0.4 ng/g ...


An Integrated Multiple Capillary Array Electrophoresis System For High-Throughput Dna Sequencing , Xiandan Lu Jan 1998

An Integrated Multiple Capillary Array Electrophoresis System For High-Throughput Dna Sequencing , Xiandan Lu

Retrospective Theses and Dissertations

Capillary array electrophoresis system was chosen to perform DNA sequencing because of several advantages such as rapid heat dissipation, multiplexing capabilities, gel matrix filling simplicity, and the mature nature of the associated manufacturing technologies;There are two major concerns for the multiple capillary systems. One concern is inter-capillary cross-talk and the other concern is excitation and detection efficiency. Cross-talk is eliminated through proper optical coupling, good focusing and immersing capillary array into index matching fluid. A side-entry excitation scheme with orthogonal detection was established for large capillary array. Two 100 capillary array formats were used for DNA sequencing. One format ...


Improved Resins And Novel Materials And Methods For Solid Phase Extraction And High Performance Liquid Chromatography , Ronald Carl Freeze Jan 1997

Improved Resins And Novel Materials And Methods For Solid Phase Extraction And High Performance Liquid Chromatography , Ronald Carl Freeze

Retrospective Theses and Dissertations

Solid-phase extraction (SPE) has grown to be one of the most widely used methods for isolation and preconcentration of a vast range of compounds from aqueous solutions. By modifying polymeric SPE resins with chelating functional groups, the selective uptake of metals was accomplished. By reducing the size of the resin beads and optimizing reaction conditions, resins were produced which had excellent capacities both in the packed-column and the suspension mode. By reducing bead sizes to 1 [mu]m, direct injection of the beads into an inductively coupled plasma (ICP) torch was possible. The resin, along with adsorbed metals, was vaporized ...


Monitoring Protein Refolding Using Diverse Separation And Spectroscopy Techniques , Pamela Kay Jensen Jan 1997

Monitoring Protein Refolding Using Diverse Separation And Spectroscopy Techniques , Pamela Kay Jensen

Retrospective Theses and Dissertations

Rapid growth in the biotechnology industry has led to a dramatic increase in attention to the protein folding problem. Understanding of protein folding is essential to the production of biopharmaceuticals since commercial production of recombinant proteins often requires a protein refolding process to recover high yields;Capillary zone electrophoresis (CZE) equipped with laser induced fluorescence detection (LIFD) is developed as a tool for monitoring the refolding of a model protein, phage P22 tailspike endorhamnosidase. Intermediates on the folding pathway are separated in CZE and monitored by their intrinsic tryptophan fluorescence. Monitoring refolding of tailspike by traditional methods, sodium dodecyl sulfate-polyacrylamide ...


Single Cell Analysis By Capillary Electrophoresis With Laser-Induced Native Fluorescence Detection , Sheri Joanne Lillard Jan 1996

Single Cell Analysis By Capillary Electrophoresis With Laser-Induced Native Fluorescence Detection , Sheri Joanne Lillard

Retrospective Theses and Dissertations

Individual mammalian cells were analyzed by capillary electrophoresis with laser-induced fluorescence detection (CE-LIF). This technique was chosen due to its high separation efficiencies, small sample volumes and sensitive detection. Native fluorescence was used, in which the analyte was not tagged with a fluorophore. 275-nm excitation gave attomole (amol = 10-18 mol) detection limits for the intracellular species of interest. Two projects are described in which hemoglobin (Hb) variants were determined in single red blood cells. In the third experiment, individual mast cells were degranulated on-column, and exocytosis and serotonin release were monitored temporally;First, single red blood cells, in which Hb ...


Applications Of Partial Filling Micellar Electrokinetic Chromatography: From Electrospray Mass Spectrometry To Fluorescence Polarization Immunodetection , Wendy Marie Nelson Jan 1996

Applications Of Partial Filling Micellar Electrokinetic Chromatography: From Electrospray Mass Spectrometry To Fluorescence Polarization Immunodetection , Wendy Marie Nelson

Retrospective Theses and Dissertations

Mechanistic studies of partial filling micellar electrokinetic chromatography PF-MEKC) and a theoretical model for the prediction of separation behavior in PF-MEKC was developed in this work. Along with the theoretical development of PF-MEKC, two different detection modes were applied to PF-MEKC, in contrast to the traditional UV detection used in micellar electrokinetic chromatography (MEKC). The first detection mode coupled PF-MEKC with eletrospray ionization mass spectrometry. The second detection mode developed in this work is PF-MEKC coupled with fluorescence polarization immunodetection;First, in the mechanistic studies of PF-MEKC a theoretical model was proposed for predicting the separation behavior of triazine herbicides ...


Optimization Of Separation And Detection Schemes For Dna With Pulsed Field Slab Gel And Capillary Electrophoresis , David Arthur Mcgregor Jan 1993

Optimization Of Separation And Detection Schemes For Dna With Pulsed Field Slab Gel And Capillary Electrophoresis , David Arthur Mcgregor

Retrospective Theses and Dissertations

The purpose of the Human Genome Project is outlined followed by a discussion of electrophoresis in both slab gels and capillaries and its application to deoxyribonucleic acid (DNA). Techniques used to modify electroosmotic flow in capillaries are also addressed. Several separation and detection schemes for DNA via gel and capillary electrophoresis are described. Emphasis is placed on the elucidation of DNA fragment size in real time as well as shortening separation times to approximate real time monitoring;First, the migration of DNA fragment bands through a slab gel can be monitored by UV absorption at 254 nm and imaged by ...


Fluorescence Detection For Gel And Capillary Electrophoresis , Barry L. Hogan Jan 1992

Fluorescence Detection For Gel And Capillary Electrophoresis , Barry L. Hogan

Retrospective Theses and Dissertations

Several separation and detection schemes for gel and capillary electrophoresis are described. Emphasis is placed upon direct and indirect fluorescence detection systems as utilized for the determination of proteins, peptides, and intracellular analytes;First, an indirect fluorescence detection system for the separation of proteins via gel electrophoresis is described. Quantities as low as 50 nanograms of bovine serum albumin and soybean trypsin inhibitor are separated and detected visually without the need for staining of the analytes. This is very similar to levels of protein commonly separated with gel electrophoresis;A separation and detection system utilizing indirect fluorescence detection with capillary ...


Novel Detection Schemes And Automated Image Analysis Algorithms For Planar Chromatography And Gel Electrophoresis , Lance Bryant Koutny Jan 1992

Novel Detection Schemes And Automated Image Analysis Algorithms For Planar Chromatography And Gel Electrophoresis , Lance Bryant Koutny

Retrospective Theses and Dissertations

After a detailed introduction to Charge Coupled Devices (CCDs) and a discussion of personal computer capabilities, examples of their applications involving novel analytical techniques are presented;A new laser-based indirect fluorometric detection method for thin-layer chromatography is demonstrated with digitally controlled two-dimensional scanning and computer-aided image acquisition and vision. Utilizing this mode, universal detection is possible without derivatization, with a detection limit of 6 pg; 100 times lower than with human vision;A detection scheme for DNA in agarose slab gel electrophoresis based on ultraviolet absorption allows for convenient in situ monitoring of conventional gels via a CCD camera system ...