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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 ...


Synthesis Of Tetrasubstituted Olefins And Aryl Ketones Via Carbopalladation Of Alkynes And Nitriles , Chengxiang Zhou Jan 2006

Synthesis Of Tetrasubstituted Olefins And Aryl Ketones Via Carbopalladation Of Alkynes And Nitriles , Chengxiang Zhou

Retrospective Theses and Dissertations

Palladium-catalyzed reactions are versatile methods for carbon-carbon bond formation due to their generality and ability to tolerate a wide range of important organic functional groups. Developing novel Palladium-catalyzed reactions has therefore been of great interest to synthetic chemists for years;The regio- and stereoselective synthesis of tetrasubstituted olefins is a long-pursuing challenge for synthetic chemists. A multi-component reaction route is ideal to generate various tetrasubstituted olefins in a very concise manner and should be highly desirable for applications in combinatorial chemistry. A highly efficient, regio- and stereoselective route to tetrasubstituted olefins has been developed by the Pd-catalyzed three-component reaction of ...


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 ...


Probing Carbohydrate Biocatalysis Through The Use Of Electrospray Ionization Mass Spectrometry And Isothermal Titration Calorimetry , Corbin James Zea Jan 2005

Probing Carbohydrate Biocatalysis Through The Use Of Electrospray Ionization Mass Spectrometry And Isothermal Titration Calorimetry , Corbin James Zea

Retrospective Theses and Dissertations

Electrospray ionization mass spectrometry,(ESI-MS)-based assays have been newly developed to study three classes of enzymes (sugar nucleotidyltransferases, glycosyltransferases, and phosphorylases) from the three distinct families of life: archaea, eukaryotes, and prokaryotes. These three classes of enzymes play vital roles in carbohydrate storage, degradation and synthesis. The sugar nucleotidyltransferases from Escherichia coli and yeast that biosynthesize UDP-glucose and ADP-glucose respectively were studied using the first ESI-MS assay. Nonlinear regression of the kinetic data was comparable to those determined from the traditional UDP-glucose dehydrogenase coupled assay. This technique allowed us to determine that the yeast sugar nucleotidyltransferase has one binding ...


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 ...


Multifunctional Mesoporous Silica Nanospheres For Biosensor, Stimuli-Responsive Controlled-Release Drug Delivery Carriers And Gene Transfection Vectors , Cheng-Yu Lai Jan 2004

Multifunctional Mesoporous Silica Nanospheres For Biosensor, Stimuli-Responsive Controlled-Release Drug Delivery Carriers And Gene Transfection Vectors , Cheng-Yu Lai

Retrospective Theses and Dissertations

Structurally well-defined mesoporous silica materials with tunable pore size and narrow pore-size distribution have attracted much attention for their potential applications in sensing, drug delivery and gene transfer. A series of mesoporous silica nanosphere-based (MSN) nano-devices were synthesized and utilized for the aforementioned applications.;For sensing application, we provide a first example in utilization of a multi-functionalized mesoporous silica material to selectively detect dopamine. A second application, rooted in this work, is the selective detection of amino-containing neurotransmitters under physiological condition.;The drug delivery applications have been built around a controlled release drug delivery device. In the original conception, the ...


Protein-Protein Interaction And Electron Transfer: Case Of Cytochrome F And Cytochrome C6 , Tijana Žarković Grove Jan 2004

Protein-Protein Interaction And Electron Transfer: Case Of Cytochrome F And Cytochrome C6 , Tijana Žarković Grove

Retrospective Theses and Dissertations

We used photo-induced reaction as a tool to look to explore dynamics of the protein-protein interaction between cytochrome f and cytochrome c6 from C. reinhardtii. In our studies of electron transfer between 3Zncyt c6 and cyt f(III) we discovered two distinct intracomplex processes corresponding to electron transfer within diprotein complexes termed persistent and transient. The overall reaction remained biphasic and the rate constants for both processes were invariant to the change of ionic strength within the studied interval. The docking of these proteins is due to strong hydrophobic interaction slightly augmented by weak electrostatic attraction. We used covalent cross-linking ...


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 ...


Complexes Of Palladium(Ii) And Platinum(Ii) As Synthetic Proteases , Nebojša M. Milović Jan 2002

Complexes Of Palladium(Ii) And Platinum(Ii) As Synthetic Proteases , Nebojša M. Milović

Retrospective Theses and Dissertations

Selective cleavage of proteins is a common procedure in many biochemical applications ranging from standard protein sequencing to novel methods in proteomics and bioengineering. Few enzymes and synthetic reagents are available for this important task, but new chemical reagents with improved efficiency and adjustable selectivity are highly desired. Complexes of palladium(II) and platinum(II), two chemically similar transition-metal ions, are new reagents for selective cleavage of peptides and proteins. The cleavage by Pd(II) complexes, such as [Pd(H2O)4]2+ or cis-[Pd(en)(H 2O)2]2+, consistently occurs in weakly acidic aqueous solutions at the amide ...


Photophysics And Light Induced Photobiology Of Antiviral And Antitumor Agents, Hypericin And Hypocrellin , Jaehun Park Jan 2001

Photophysics And Light Induced Photobiology Of Antiviral And Antitumor Agents, Hypericin And Hypocrellin , Jaehun Park

Retrospective Theses and Dissertations

The dissertation mainly focuses on the excited-state photophysics and the light-induced biological activity of hypericin and its analogs.;Femtosecond laser technology has provided the opportunity to investigate the rapid dynamics of these molecules. Fluorescence upconversion measurements, which monitor only emission from the fluorescent singlet state, demonstrate that hexamethoxy hypericin, which possesses no labile protons, has an instantaneous rise time for its transient response. On the other hand, hypericin shows a clear 10-ps rise time. This confirms excited-state H-atom transfer as the primary photophysical process in hypericin.;Femtosecond transient absorption spectroscopy technique is used to determine if excited state H-atom transfer ...


Interactions And Electron-Transfer Reactions Between Metalloproteins , Milan Miroslav Crnogorac Jan 2000

Interactions And Electron-Transfer Reactions Between Metalloproteins , Milan Miroslav Crnogorac

Retrospective Theses and Dissertations

Electron-transfer reactions are essential for life. Because metalloproteins are involved in electron transport in the cell, it is important to understand the factors that affect recognition, interaction, and reactions of these electron carriers. Cytochrome c is well-characterized electron-carrier protein. The heme protein cytochrome c and the blue-copper protein plastocyanin are well suited for kinetic and mechanistic studies since their structures are known in detail;We investigated the effects of site-directed mutations and viscosity on rate-limiting rearrangement within the complex of cytochrome c and plastocyanin and identified the reactive configuration of the complex. In the reactive configuration of the complex cytochrome ...


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 ...


Primary Photoprocesses Of Light-Activated Antiviral And Antitumor Agents, Hypericin And Hypocrellin , Alexandre V. Smirnov Jan 1999

Primary Photoprocesses Of Light-Activated Antiviral And Antitumor Agents, Hypericin And Hypocrellin , Alexandre V. Smirnov

Retrospective Theses and Dissertations

The dissertation focuses on the ultrafast primary photoprocesses of the title anti-viral and anti-cancer agents, whose activity depends on light which is also accompanied by photoacidification in vesicles and living cells;By complementing the techniques of time-resolved absorption spectroscopy with those of fluorescence upconversion and applying them to hypericin, hypocrellin A and B, and their methylated analogs that are unable to execute proton transfer, it was demonstrated that intramolecular excited-state hydrogen atom transfer is a dominant primary nonradiative process;For hypocrellin A in viscous solvents such as octanol and ethylene glycol, an absorption transient of ∼10-ps duration, similar to the ...


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 ...


Application Of Spectral Hole Burning To The Study Of In Vitro Cellular Systems , Nebojsa Milanovich Jan 1999

Application Of Spectral Hole Burning To The Study Of In Vitro Cellular Systems , Nebojsa Milanovich

Retrospective Theses and Dissertations

The high resolution spectroscopic technique of nonphotochemical hole burning (NPHB) was applied to the study of in vitro cellular systems. Suspensions of two well-characterized cell lines were used for these studies: (1) MCF-10F cells, a normal human breast epithelial cell line, and (2) MCF-7 cells, a human breast adenocarcinoma cell line. Both cell lines were stained with the dye aluminum phthalocyanine tetrasulfonate (APT) and prepared for spectroscopic study at liquid helium temperatures. Routinely measured hole burning parameters were obtained for the two cell types and compared in order to differentiate between physical properties of normal and cancer cells;A comparison ...


Theoretical Simulations And Ultrafast Pump-Probe Spectroscopy Experiments In Pigment-Protein Photosynthetic Complexes , Daniel Richard Buck Jan 1998

Theoretical Simulations And Ultrafast Pump-Probe Spectroscopy Experiments In Pigment-Protein Photosynthetic Complexes , Daniel Richard Buck

Retrospective Theses and Dissertations

Theoretical simulations and ultrafast pump-probe laser spectroscopy experiments were used to study photosynthetic pigment-protein complexes and antennae found in green sulfur bacteria such as Prosthecochloris aestuarii, Chloroflexus aurantiacus, and Chlorobium tepidum. The work focused on understanding structure-function relationships in energy transfer processes in these complexes through experiments and trying to model that data as we tested our theoretical assumptions with calculations;Theoretical exciton calculations on tubular pigment aggregates yield electronic absorption spectra that are superimpositions of linear J-aggregate spectra. The electronic spectroscopy of BChl c/d/e antennae in light harvesting chlorosomes from Chloroflexus aurantiacus differs considerably from J-aggregate spectra ...


Hole Burning With Pressure And Electric Field: A Window On The Electronic Structure And Energy Transfer Dynamics Of Bacterial Antenna Complexes , Hsing-Mei Wu Jan 1998

Hole Burning With Pressure And Electric Field: A Window On The Electronic Structure And Energy Transfer Dynamics Of Bacterial Antenna Complexes , Hsing-Mei Wu

Retrospective Theses and Dissertations

Light-harvesting complexes of cyclic symmetry from purple bacteria are studied using absorption and high pressure- and Stark-hole burning spectroscopies. The B800→B850 energy transfer rate of (~2 ps)-1 determined by hole burning and pump-probe spectroscopies is weakly dependent on B800-B850 energy gap varied by pressure and temperature. This resilience is explained in terms of a modified Forster theory with the spectral overlap provided by the B800 fluorescence origin band and weak vibronic absorption of B850. Explanations for the additional sub-picosecond relaxation channel of B800 with excitation on the blue side are given. Pressure and temperature dependent studies show that ...


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 ...


X-Ray Crystallographic Studies On Adenylosuccinate Synthetase From Escherichia Coli , Zhenglin Hou Jan 1998

X-Ray Crystallographic Studies On Adenylosuccinate Synthetase From Escherichia Coli , Zhenglin Hou

Retrospective Theses and Dissertations

Adenylosuccinate synthetase catalyzes the first committed step in de novo biosyntheses of AMP from IMP and aspartate, using GTP as the energy source. Metal cations, ligand-induced conformational transitions and metabolic effectors significantly influence the catalytic potential of the synthetase. The Mg2+, Mn2+, or Ca 2+ bind to the same site, coordinating alpha-, beta-, and gamma-phosphoryl groups of GTP. The level of catalysis supported by each cation is linked to its influence on the basicity of Asp13, a residue which abstracts the proton from N1 of IMP. Zn2+, a potent inhibitor of the synthetase, coordinates the beta- and gamma-phosphoryl groups of ...


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 ...


Characterization Of Biomacromolecules By Nuclear Magnetic Resonance Spectroscopy , Wayne Robert Baker Jan 1996

Characterization Of Biomacromolecules By Nuclear Magnetic Resonance Spectroscopy , Wayne Robert Baker

Retrospective Theses and Dissertations

Two proteins were examined by Nuclear Magnetic Resonance (NMR) spectroscopy. The Emb-1 protein of Daucus carota was found to have few spectral characteristics indicative of a stable tertiary structure. In particular, line-widths were narrow, chemical shift dispersion was poor and nuclear Overhauser effect spectra were sparse. The NMR spectra of Ribonuclease A was examined at a range of pH values and the chemical shifts of a selected number of resonances was plotted as a function of the pH. From these titrations curves pKa values were determined and assigned to specific ionizing groups within the protein based, in part, on physical ...


Effects Of Ear Developmental Temperature On Fine Structure Of Maize Starch , Ting-Jang Lu Jan 1995

Effects Of Ear Developmental Temperature On Fine Structure Of Maize Starch , Ting-Jang Lu

Retrospective Theses and Dissertations

Two genetically unrelated normal dent maize inbreds, ICI63 and ICI92, with different heterotic backgrounds were used for studying environmental temperature effects on grain yield and quality. These two maize inbreds are used in commercially available hybrids and are proprietary to ICI Seeds. The maize inbreds were grown in a greenhouse to control the growing condition of the plants. After 14 days post-pollination, the ears were wrapped in temperature control devices set at 25 or 35∘ C during the grain-filling period. Grain yield, kernel weight, and kernel density were less for ears developing at 35∘ C than for those at 25 ...


Photophysics And Activity Of Biological Systems Containing The Optical Probes 7-Azatryptophan And Its Analogs , Rebecca Lynne Rich Jan 1995

Photophysics And Activity Of Biological Systems Containing The Optical Probes 7-Azatryptophan And Its Analogs , Rebecca Lynne Rich

Retrospective Theses and Dissertations

A major use of photophysical apparatus is the study of biological systems, for example, peptides, proteins, and DNA, that contain one or more chromophores. In recent years the incorporation of nonnatural fluorescent compounds into these systems has gained great popularity. A number of optical 'tags' have been suggested as detection tools of structure and function; we propose the use of the tryptophan derivative, 7-azatryptophan, as an intrinsic probe in photophysical analyses of proteins. Not only is this chromophore spectroscopically distinct from tryptophan and all other natural amino acids, but we have demonstrated the successful incorporation of 7-azatryptophan into peptide sequences ...


Line Narrowing Spectroscopic Studies Of Dna-Carcinogen Adducts And Dna-Dye Complexes , Myungkoo Suh Jan 1995

Line Narrowing Spectroscopic Studies Of Dna-Carcinogen Adducts And Dna-Dye Complexes , Myungkoo Suh

Retrospective Theses and Dissertations

Laser-induced fluorescence line narrowing (FLN) and non-line narrowing (NLN) spectroscopic methods were applied to conformational studies of stable DNA adducts of the 7[beta],8[alpha]-dihydoxy-9[alpha],10[alpha]-epoxy-7,8,9, 10-tetrahydrobenzo (a) pyrene (anti-BPDE). Stereochemically distinct (+)-trans-, (-)-trans-, (+)-cis- and (-)-cis adducts of anti-BPDE bound to exocyclic amino group of the central guanine in the oligonucleotide, 5'-d(CCATCGCTACC) · (GGTAGCGATGG), exist in a mixture of conformations in frozen aqueous buffer matrices. The (+)-trans adduct adopts primarily an external conformation with a smaller fraction (~25%) exists in a partially base-stacked conformation. Both cis adducts were found to be ...