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Articles 1 - 21 of 21

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

Monolayer Studies Of Novel Synthetic Compounds And Biological Systems , Jingyuan Wang Jan 1994

Monolayer Studies Of Novel Synthetic Compounds And Biological Systems , Jingyuan Wang

Retrospective Theses and Dissertations

A general review on preparation and methods of characterization of monolayers was given in Chapter 1. Different projects were undertaken in the research of this dissertation. Neutron and X-ray reflection studies of fullerene C[subscript]60 and its derivative monolayers were performed in Chapter 1. Neutron and X-ray reflection measurements and surface pressure isotherms of spread films of C[subscript]60-dodecylamine adduct C[subscript]60-(NH[subscript]2(CH[subscript]2)[subscript]11CH[subscript]3][subscript]x and C[subscript]60-propylamine adduct C[subscript]60-(NH[subscript]2C[subscript]3H[subscript]7][subscript]x indicate that these C[subscript]60 ...


Purification, Characterization And Cloning Of A Periplasmic Catalase From B Abortus And The Role It Plays In The Pathogenesis Of Brucella , Zheng Yu Sha Jan 1994

Purification, Characterization And Cloning Of A Periplasmic Catalase From B Abortus And The Role It Plays In The Pathogenesis Of Brucella , Zheng Yu Sha

Retrospective Theses and Dissertations

A periplasmic catalase has been identified and purified from Brucella abortus using a procedure which fractionates periplasmic B. abortus proteins from other cellular components while retaining biological activity. The biochemical characteristics of the purified enzyme were studied and the gene encoding the enzyme cloned and sequenced. SDS polyacrylamide gel electrophoresis of the purified enzyme revealed only a single subunit with a molecular weight of 59,000. Gel filtration indicates the native protein is a tetramer. The native protein has a visible absorption spectrum with maxima at 407, 501, and 628 nm which is typical of mammalian, but not some bacterial ...


Molecular Mechanisms Of Mycoplasma Hyopneumoniae Adherence To Swine Respiratory Epithelial Cells, Qijing Zhang Jan 1994

Molecular Mechanisms Of Mycoplasma Hyopneumoniae Adherence To Swine Respiratory Epithelial Cells, Qijing Zhang

Retrospective Theses and Dissertations

A microtiter plate adherence assay for Mycoplasma hyopneumoniae was established by using purified swine tracheal cilia which are the natural targets for the mycoplasma. M. hyopneumoniae bound specifically to solubilized cilia immobilized onto microtiter plates. Dextran sulfate, heparin, chondroitin sulfate, laminin, mucin, and fucoidan significantly inhibited binding of the mycoplasmas to cilia. Heparin, mucin, fucoidan, and chondroitin sulfate interacted with the adhesins on the surface of mycoplasmas, whereas laminin blocked the receptors in cilia. Treatment of cilia with neuraminidase appeared to promote adherence of the mycoplasmas; whereas, treatment of cilia with sodium metaperiodate decreased the binding. In the second study ...


Identification Of Potential Oat Phytochrome A Mrna Degradation Mechanisms , David Charles Higgs Jan 1994

Identification Of Potential Oat Phytochrome A Mrna Degradation Mechanisms , David Charles Higgs

Retrospective Theses and Dissertations

The phytochrome plant photoreceptor is important for perceiving the light environment and initiating plant developmental and environmental responses. When dark-grown oat seedlings are treated with light the phytochrome A (PHYA) mRNA abundance rapidly declines due, in part, to the inherent instability of the PHYA mRNA. Messenger RNA stability is an important process in regulating eukaryotic gene expression. My primary goal was to investigate both the mechanism of oat PHYA mRNA degradation and cis-acting sequences involved in regulating oat PHYA mRNA degradation. An oat protoplast system was established to investigate its use as a quick and reliable system to study plant ...


G-Wires: The Growth And Characterization Of A G4-Dna Nanostructure , Thomas Cosgrove Marsh Jan 1994

G-Wires: The Growth And Characterization Of A G4-Dna Nanostructure , Thomas Cosgrove Marsh

Retrospective Theses and Dissertations

Guanine-rich sequences are vital components in the genomes of many organisms. For example, G-rich sequences are found in telomeres, fragile X locus, promoters, IgG switch regions, recombinational hot spots and the HIV RNA dimerization domain. The functions of these G-rich sequences rely in part on guanine self-recognition. G-rich sequences can adopt a quadruple helical conformation in the presence of specific monovalent and divalent metal cations which are also required for maintaining the quadruplex stability. The structural basis of the quadruplex is a cyclic Hoogsteen hydrogen bonded guanine tetrad known as the G-quartet. Sequences capable of forming G-quartets are classified as ...


Cooperative Binding By A Self-Assembled Receptor: Metal In A Structural And Functional Role , Jin-Ho Lee Jan 1994

Cooperative Binding By A Self-Assembled Receptor: Metal In A Structural And Functional Role , Jin-Ho Lee

Retrospective Theses and Dissertations

Metal complexes of the amino acid, 4,4[superscript]'-phosphinylidine bis phenylalanine (PBP*, 1), self-assemble to produce a macrocyclic receptor (Co[subscript]2PBP[subscript]2, 2) with a hydrophobic cavity capable of binding aromatic compounds from water. Here we demonstrate that the metal can play a structural and a functional role: the receptor binds substrates bearing both aromatic and polar functional groups ditopically, using the hydrophobic pocket as well as the metal itself. The doubly anionic Co[superscript]2+ macrocyclic complex binds neutral aromatic guests more tightly than it does most anionic guests, as would be expected. However, carboxylates tethered ...


Telomeric Nucleic Acids: C-Strand Structure And A Telomerase Rna Mutant , Shawn Cameron Ahmed Jan 1994

Telomeric Nucleic Acids: C-Strand Structure And A Telomerase Rna Mutant , Shawn Cameron Ahmed

Retrospective Theses and Dissertations

Telomeres, the ends of linear chromosomes, are composed of simple tandem repeats which are usually G·C rich. Telomeres are essential for chromosome stability, organizing the nuclear architecture and ensuring complete replication of the chromosomal terminus. To understand how telomeres carry out these fundamental cellular roles, one must understand the structural and dynamic properties of telomeric repeat sequences. Structural and genetic approaches were taken to learn more about telomeric nucleic acids;The structural portion of my research concerned an unusual DNA structure formed by the C-rich strand of telomeric DNA. Telomeric C-strand sequences form non-Watson-Crick structures in supercoiled plasmids at ...


Expression Of Chlamydomonas Reinhardtii Periplasmic Carbonic Anhydrase In Escherichia Coli And Transgenic Tobacco Plants , Cyril Sebastian Roberts Jan 1994

Expression Of Chlamydomonas Reinhardtii Periplasmic Carbonic Anhydrase In Escherichia Coli And Transgenic Tobacco Plants , Cyril Sebastian Roberts

Retrospective Theses and Dissertations

Carbonic anhydrase (CA) catalyzes the reversible hydration of CO2. The periplasmic CA gene CAH1 of Chlamydomonas reinhardtii codes for a highly processed secreted glycoprotein. The primary translation product of the CAH1 gene is targeted to the algae's ER, where it is proteolytically processed to yield two different subunits, glycosylated, assembled into an active heterotetramer, and secreted. Expression of CAH1 in Escherichia coli and tobacco plants were effected in this study. For bacterial expression, two constructs, one with and another without, the algal target leader sequence were used. Similarly, after replacing the algal's target leader sequence with that from ...


Regulation Of Mitogen Regulated Protein/Proliferin Gene Expression In 3t3 Cells By Basic Fibroblast Growth Factor , Manzoor Ali P. K. Mohideen Jan 1994

Regulation Of Mitogen Regulated Protein/Proliferin Gene Expression In 3t3 Cells By Basic Fibroblast Growth Factor , Manzoor Ali P. K. Mohideen

Retrospective Theses and Dissertations

Mitogen regulated protein/proliferin (MRP/PLF) is a murine uterine growth factor belonging to the prolactin/growth hormone gene superfamily. Basic fibroblast growth factor (bFGF) regulates its expression in 3T3 cells and is speculated to be among its regulators in vivo. In order to gain insights into its regulation, experiments were performed to elucidate the mechanisms by which bFGF regulates mrp/plf gene expression in 3T3 cells. RT-PCR analyses demonstrated that of the three different forms of MRP/PLF proteins only one, PLF1, is expressed in these cells in response to bFGF. PLF1 could be the product of either plf42 ...


Characterization And Immunogenicity Of The Heat Shock Protein, Hsp60 Of Brucella Abortus , Dennis Gor Jan 1994

Characterization And Immunogenicity Of The Heat Shock Protein, Hsp60 Of Brucella Abortus , Dennis Gor

Retrospective Theses and Dissertations

Brucella abortus is the causative agent of bovine brucellosis, a disease that causes spontaneous abortion in cows. The most effective form of protection against this pathogen is immunization; however, Brucella abortus strain 19 (the standard vaccine against Brucella abortus) is not completely protective. The vaccination of laboratory mice with the heat shock protein, hsp60 derived from Brucella abortus, using live attenuated recombinant Salmonella typhimurium expressing this protein (hsp60) as a delivery system, and the characterization of the immune response to Brucella abortus hsp60 over a 12 week time course following vaccination is described;Infection of BALB/c strain of laboratory ...


Molecular And Ultrastructural Aspects Of The Adaptation Of Chlamydomonas Reinhardtii To Limiting Co2 , Anne Margaret Geraghty Jan 1994

Molecular And Ultrastructural Aspects Of The Adaptation Of Chlamydomonas Reinhardtii To Limiting Co2 , Anne Margaret Geraghty

Retrospective Theses and Dissertations

Change occurring in Chlamydomonas reinhardtii as cells adapt to limiting CO2 conditions were examined at both a molecular level and an ultrastructural level. It was demonstrated using antibodies that the time course of the de novo synthesis of LIP-21, a 21 kD limiting-CO2 induced polypeptide, correlates with the appearance of CO2 concentrating activity and that expression of the nuclear gene for LIP-21 is regulated at the level of translatable message. These results are consistent with LIP-21 being a component of an adaptive response to limiting CO2, such as the induction of the CO2 concentrating mechanism. Phase separation of membrane proteins ...


Oat Phya Containing Transgenic Tobacco: An Examination Of Oat Phya Mrna Stability And The Role Of Oat Phya In Germination Of Tobacco Seed , Linda Joanne Barnes Jan 1994

Oat Phya Containing Transgenic Tobacco: An Examination Of Oat Phya Mrna Stability And The Role Of Oat Phya In Germination Of Tobacco Seed , Linda Joanne Barnes

Retrospective Theses and Dissertations

The regulation of oat phytochrome A (phyA) mRNA stability and the photoregulation of germination of tobacco seeds containing the oat phyA gene was examined using oat phyA containing transgenic tobacco. Oat phyA mRNA has been previously shown to be a relatively unstable mRNA. The intent of this research was to identify elements within the phyA mRNA responsible for rendering the message unstable. The approach taken was to use tobacco transformed with either the full-length or truncated versions of the oat phyA gene and examine the half-lives of the resulting oat phyA mRNAs in transgenic tobacco. RNA blot analysis of oat ...


Genetic Analysis Of Pseudohyphal Growth In The Budding Yeast Saccharomyces Cerevisiae , Melissa Jo Blacketer Jan 1994

Genetic Analysis Of Pseudohyphal Growth In The Budding Yeast Saccharomyces Cerevisiae , Melissa Jo Blacketer

Retrospective Theses and Dissertations

The budding yeast Saccharomyces cerevisiae is a dimorphic organism that can assume either a yeast-like or pseudohyphal form. Nitrogen limitation induces pseudohyphal growth, which is characterized by branched chains of elongated cells. Pseudohyphal cells can grow invasively in agar medium, whereas yeast-like cells do not. To identify factors involved in morphologic differentiation, S. cerevisiae mutants exhibiting a constitutive cell elongation morphology were isolated. Genetic analysis identified 28 recessive and 2 semi-dominant mutations that cause abnormal morphology, and placed these in 14 distinct gene loci, termed ELM, for ELongated Morphology. Many elm mutations cause multiple aspects of pseudohyphal growth, and thus ...


Soybean Cultivar Development: A Genome Perspective , Lisa Lou Lorenzen Jan 1994

Soybean Cultivar Development: A Genome Perspective , Lisa Lou Lorenzen

Retrospective Theses and Dissertations

The purpose of this dissertation was to retrospectively analyze the process of soybean cultivar development from a molecular perspective, by following the inheritance of RFLP markers in a pedigree analysis. Five methods of analysis are included in this dissertation;Sixty-four plant introductions, cultivars, and breeding lines were analyzed to define a core set of 97 probes with a high likelihood of detecting a polymorphism in elite germplasm. The ability to trace regions of chromosomes from parent to offspring and the application of pedigree-based mapping was demonstrated, which is the cosegregation of phenotypic traits and RFLP markers based on pedigree information ...


Molecular Characterization Of Porcine Respiratory Coronavirus Isolates With Varying Pathogenicity , Eric Martin Vaughn Jan 1994

Molecular Characterization Of Porcine Respiratory Coronavirus Isolates With Varying Pathogenicity , Eric Martin Vaughn

Retrospective Theses and Dissertations

Three new isolates of porcine respiratory coronavirus (PRCV) were isolated and characterized. Two of the PRCV isolates, AR310 and LEPP, were shown to produce moderate interstitial pneumonia, whereas the third PRCV isolate, IA1894, was only mildly pathogenic in five-week-old specific pathogen free pigs. The previously described PRCV isolate ISU-1, a mildly pathogenic PRCV isolate, was also included in this study. These PRCV isolates with varying pathogenicity provided an opportunity to determine if there are certain genes that correlate with virulence, as the genes 3 and 3-1 have been hypothesized to be virulence determinants for transmissible gastroenteritis virus (TGEV) isolates. Using ...


Expression, Purification, Characterization, And Site-Directed Mutagenesis Of Phosphorylase Kinase [Upsilon] Subunit , Chi-Ying F. Huang Jan 1994

Expression, Purification, Characterization, And Site-Directed Mutagenesis Of Phosphorylase Kinase [Upsilon] Subunit , Chi-Ying F. Huang

Retrospective Theses and Dissertations

The overall aim was to elucidate the substrate specificity and regulatory properties of the catalytic subunit of phosphorylase kinase (PhK) to better understand how this enzyme works. I have expressed the PhK [gamma] subunit (full-length and seven truncated forms) in E. coli. One of the truncated forms of [gamma], [gamma][subscript]1-300 has a 2-fold higher specific activity than the full-length [gamma], suggesting that an autoinhibitory domain(s) is located at the C-terminus of [gamma], [gamma][subscript]301-386. The truncated [gamma][subscript]1-300 purified to homogeneity has several properties similar to full-length [gamma], including its substrate specificity and metal ion ...


Biochemical Characterization Of Plant Biotin-Containing Enzymes , Tomás Alberto Diez Jan 1994

Biochemical Characterization Of Plant Biotin-Containing Enzymes , Tomás Alberto Diez

Retrospective Theses and Dissertations

3-Methylcrotonyl-CoA carboxylase has been purified and characterized from maize leaves. The enzyme is composed of two subunits, a biotin-containing polypeptide of 80 kDa, and a nonbiotin-containing polypeptide of 58 kDa. The native molecular weight of the holoenzyme is estimated at 853,000. The enzyme probably has an [alpha][subscript]6[beta][subscript]6 configuration. The kinetic constants for the substrates of 3-methylcrotonyl-CoA and its pH optimum were determined. The enzyme is allosterically activated by Mg[superscript]2+ and nonessentially activated by monovalent cations. The enzyme is strongly inhibited by acetoacetyl-CoA and by arginyl and sulfhydryl modifying reagents;The effect of ...


Photophysics Of A Novel Optical Probe-7-Azatryptophan And Its Application In The Study Of Protein-Protein Interactions , Yu Chen Jan 1994

Photophysics Of A Novel Optical Probe-7-Azatryptophan And Its Application In The Study Of Protein-Protein Interactions , Yu Chen

Retrospective Theses and Dissertations

Time-resolved and steady-state fluorescence study of the biological optical probe, 7-azatryptophan, its chromophoric moiety 7-azaindole are performed in order to explain the observation that the fluorescence spectrum of 7-azaindole (7-azatryptophan) apparently consists of one band in water ([lambda][subscript]sp\max em = 386nm) whereas in alcohols the spectrum is bimodal (eg. for methanol, [lambda][subscript]sp\max em = 374, 505nm). Careful measurements of the fluorescence decay as a function of emission wavelength indicate a small amplitude of an ~70 ps decaying component at the bluer wavelength and a rising component of the same duration at the redder wavelengths. The small ...


Sensitive Detection And Study Of Catalytic Species For Bimolecular Reactions , James William Lane Jan 1994

Sensitive Detection And Study Of Catalytic Species For Bimolecular Reactions , James William Lane

Retrospective Theses and Dissertations

In our lab, we have developed a sensitive and convenient assay for the detection of catalysts for bimolecular reactions. We have shown that catalysis of peptide synthesis by as little as 2.5 fmol (2.5 x 10[superscript]-15 mol) of a damaged enzyme can be detected using our assay. An interesting feature of our procedure is that it requires no complex apparatus, and may be carried out in parallel on many samples. We have used the assay to detect the presence of an enzyme catalyst, however the basic assay design is very versatile and may also be used ...


Structure And Function Of Unmodified E. Coli Valine-Trna , Dongxian Yue Jan 1994

Structure And Function Of Unmodified E. Coli Valine-Trna , Dongxian Yue

Retrospective Theses and Dissertations

The effects of nucleoside modifications on E. coli tRNA[superscript]Val structure have been probed by imino [superscript]1H NMR. The NMR data shows that the structure of in vitro transcribed (unmodified) and native (modified) tRNA[superscript] Val are very similar in 15 mM Mg[superscript]2+. Temperature dependence of the spectra reveals that nucleoside modifications stabilize tertiary interactions between T and D loops. On removal of Mg[superscript]2+, unmodified tRNA[superscript] Val undergoes remarkable structural changes which are not observed in native tRNA[superscript] Val. There is near total disruption of the D stem and of tertiary interactions ...


Dethiolation Of Protein Mixed-Disulfides , Che-Hun Jung Jan 1994

Dethiolation Of Protein Mixed-Disulfides , Che-Hun Jung

Retrospective Theses and Dissertations

The dithiol proteins, glutaredoxin, thioredoxin, and protein disulfide isomerase, were examined as dethiolases (i.e., reductases for protein mixed-disulfides) by studying the specificity and reactivity for an S-glutathiolated protein mixture. The 35S-glutathiolated protein mixture was prepared from 35S-labeled rat hepatocytes by diamide treatment. Dethiolation of individual 35S-labeled proteins was analyzed by combining SDS-PAGE and autoradiography. The dithiol proteins greatly enhanced dethiolation rates and could completely dethiolate all of the S-glutathiolated proteins. The dethiolation rate for individual proteins by each dithiol protein was compared and glutaredoxin was the most effective for every S-glutathiolated hepatocyte protein. When testing the reduction of insulin ...