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Articles 1 - 18 of 18

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

Mutational Analysis Of Aspergillus Awamori Glucoamylase Selectivity To Improve Glucose Yield , Hsuan-Liang Liu Jan 1998

Mutational Analysis Of Aspergillus Awamori Glucoamylase Selectivity To Improve Glucose Yield , Hsuan-Liang Liu

Retrospective Theses and Dissertations

Three single mutations, Lys108→Arg, Lys108→Met and Tyr312→Trp, and one insertional mutation, 322-314 Loop, in Aspergillus awamori glucoamylase were constructed and tested along with four previously constructed thermostable mutations: Asn20→Cys/Ala27→Cys (SS), Ser30→Pro, Gly137→Ala, and Ser436→Pro, and one previously made thermosensitive mutation, Ala27→Pro, for their selectivity by high-concentration glucose condensation and maltodextrin hydrolysis reactions. Lys108 is important in substrate binding during maltooligosaccharide hydrolysis. Both SS and 311-314 Loop mutant GAs successfully decrease isomaltose formation rate and thus increase peak glucose yield. Tyr312→Trp GA helps to form a tighter hydrogen bond network ...


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 ...


Isolation And Characterization Of Genes Belonging To Developmental Regulatory Gene Classes In Potato (Solanum Tuberosum L.) , Jennifer Krulic Hart Jan 1998

Isolation And Characterization Of Genes Belonging To Developmental Regulatory Gene Classes In Potato (Solanum Tuberosum L.) , Jennifer Krulic Hart

Retrospective Theses and Dissertations

Although plant growth is an important topic, the regulation of genes involved in growth is poorly understood. To contribute to current information about plant growth regulation, an early tuberization cDNA library from Solanum tuberosum L., expected to contain genes involved in cell proliferation, was screened for members of developmental regulatory gene families. The two objectives of this study were to isolate genes that might be involved in plant growth regulation, and to characterize the RNA accumulation patterns of these genes to gain insight into their function. The AAA-protein superfamily ATPase POTATP1 and the homeobox gene POTH1 were isolated to accomplish ...


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 ...


On-Line Coupling Of Capillary Electrophoresis And Liquid Chromatography With Electrospray Ionization Mass Spectrometry For Protein Characterization , Liyu Yang Jan 1998

On-Line Coupling Of Capillary Electrophoresis And Liquid Chromatography With Electrospray Ionization Mass Spectrometry For Protein Characterization , Liyu Yang

Retrospective Theses and Dissertations

On-line coupling of capillary isoelectric focusing (CIEF) and liquid chromatography (LC) with electrospray ionization mass spectrometry (ESIMS) is utilized for protein characterization;A microdialysis junction, based on a microdialysis membrane connecting both a separation capillary and a short, sharply tapered microelectrospray emitter capillary, is demonstrated for CIEF-ESIMS. Besides the electrical connection across the microdialysis junction, post-run acidification via the dialysis membrane is demonstrated for enhancing the protonation and the ionization efficiency of focused proteins while maintaining separation efficiency, resolution, and sensitivity in CIEF-ESIMS;On-line combination of CIEF with ESI-FTICRMS is demonstrated for high resolution analysis of model proteins, human hemoglobin ...


Analysis Of Viral Proteins Of Porcine Reproductive And Respiratory Syndrome Virus In Host Protection And Early Virus-Cell Interactions , Yanjin Zhang Jan 1998

Analysis Of Viral Proteins Of Porcine Reproductive And Respiratory Syndrome Virus In Host Protection And Early Virus-Cell Interactions , Yanjin Zhang

Retrospective Theses and Dissertations

The viral proteins of porcine reproductive and respiratory syndrome virus (PRRSV) were expressed in a baculovirus expression system. They were evaluated for protection of pigs against the respiratory disease and for function in virus-cell interactions. The open reading frames 2 to 6 products were confirmed to be membrane associated proteins as they were detected on the surface of viable insect cells by an immunofluorescence assay. Immunization of pigs with vaccines comprised of a combination of GP2, GP3 and GP4 or a combination of GP5, M and N proteins induced partial protection, but immunization with combination of GP5 and M proteins ...


Characterization Of Starch Debranching Enzymes Of Maize Endosperm , Afroza Rahman Jan 1998

Characterization Of Starch Debranching Enzymes Of Maize Endosperm , Afroza Rahman

Retrospective Theses and Dissertations

The goal of this research is to understand the biochemical lesion of the sugary1 mutation in maize. The sugary1 gene is a determinant of starch structure. Homozygous su1-mutant endosperms accumulate a highly-branched water-soluble polysaccharide, phytoglycogen, at the expense of amylopectin. These suggest that both branched polysaccharides share a common biosynthetic pathway, and that SU1 participates in the biosynthesis of kernel starch. Specific antibodies were used to demonstrate that SU1 is a 79-kD protein that accumulates in endosperm during starch biosynthesis. Recombinant near full-length SU1 (SU1r) was expressed in E. coli and purified to apparent homogeneity. Determination of substrate specificity of ...


Characterization Of Three Root Hair Mutants In Maize , Tsui-Jung Wen Jan 1998

Characterization Of Three Root Hair Mutants In Maize , Tsui-Jung Wen

Retrospective Theses and Dissertations

Root hairs are thought to play an important role in the uptake of water and nutrients from the environment. Several root hair defective mutants were isolated from Mutator-tagged stocks and EMS-mutagenized lines of maize. These mutants all condition either non-elongated root-hair initials (rth1, rth3-1, rth3-2, rth3-3, rth4, rth5, rth6) or shorter-than-normal root hairs (rth2). The morphology of rth1, rth2, and rth3 root hairs were analyzed via SEM. The rth1, rth2, and rth3 genes map to chromosomes 1L, 5L, and 1S, respectively. The rth3 gene was cloned using Mu-tagged allele. The partial cDNA sequence of this gene suggests that it may ...


The Poplar-Leaf Rust Pathosystem: Inheritance Of Resistance And Pathogenic Variability , Girma Melesse Tabor Jan 1998

The Poplar-Leaf Rust Pathosystem: Inheritance Of Resistance And Pathogenic Variability , Girma Melesse Tabor

Retrospective Theses and Dissertations

Among diseases that cause serious yield reduction on Populus deltoides is leaf rust caused by Melampsora medusae. The objectives of this project were to study the pathogenic variability of M. medusae, the genetic basis of inheritance of M. medusae resistance in a family of P. deltoides; and to identify molecular markers linked to a leaf-rust resistant locus. Three pathotypes of M. medusae were identified on the basis of their differential reaction to three Populus clones. Pathotypes D-93, F-93, and IL-48 were compatible with clone 1-488 (P. X euramericana). F-93 and IL48 were also compatible with clone 57-276 (P. deltoides X ...


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 ...


Investigating The Mechanism Of Mrp/Plf Gene Expression By Bfgf , Alesia Marie Hruska-Hageman Jan 1998

Investigating The Mechanism Of Mrp/Plf Gene Expression By Bfgf , Alesia Marie Hruska-Hageman

Retrospective Theses and Dissertations

The mitogen-regulated protein/proliferin (mrp/ plf) genes belong to the prolactin/growth hormone gene superfamily and encode at least four closely related proteins. Identified functions of these proteins include stimulation of uterine proliferation and endothelial angiogenesis. In 3T3 cells, basic fibroblast growth factor (bFGF) stimulates the production of mrp/plf mRNAs with a resulting increase in the protein products. Although the three cloned mrp/ plf gene promoters (mrp3, plf42, and plf149 ) are over 97% identical in sequence, only mrp3 is transcriptionally activated by bFGF. We have identified a sequence in the mrp3 promoter, which we have named the "bFGF-responsive element ...


Genetic Analysis Of Quantitative Trait Loci With The Early Generations Of An Elite, Single-Cross Maize Population , Dwi Asmono Jan 1998

Genetic Analysis Of Quantitative Trait Loci With The Early Generations Of An Elite, Single-Cross Maize Population , Dwi Asmono

Retrospective Theses and Dissertations

The first objective of this study was to detect QTLs affecting agronomically important traits in the F2 plants of an elite, single-cross of maize (Zea mays L.). The second objective was to compare QTL detection in the F2 and F2:3 generations. The third objective was to compare QTL detection in two samples of F2:3 lines derived from the same F2 population;Thirty-eight QTLs affecting five traits were identified in the F2 plants. The QTLs were associated with 6 to 43% of the phenotypic variation. QTLs explaining more than 40% of the variation were observed for plant height and ...


Reversible Palmitoylation Of H-Ras Is Affected By Oxidants And Activation State , Tara Lynn Baker Jan 1998

Reversible Palmitoylation Of H-Ras Is Affected By Oxidants And Activation State , Tara Lynn Baker

Retrospective Theses and Dissertations

Signal transduction organizes cell growth, differentiation, and apoptosis. One component of several signaling pathways leading to these outcomes is the Ras protein. Ras is a small GTPase, binding GTP in an active conformation and GDP in an inactive conformation. Upon nucleotide binding, the conformation of Ras changes so that its effector region can bind to proteins directly downstream in several pathways. Several GTP-bound mutants have been discovered, and an activated Ras mutant has been found in at least 50% of human tumors;Ras must reside at the membrane in order to interact with effector proteins. Binding at the plasma membrane ...


Epigenetic Effects Of Matrix Attachment Regions On Transgene Expression In A Maize Callus Line , Cory Ray Brouwer Jan 1998

Epigenetic Effects Of Matrix Attachment Regions On Transgene Expression In A Maize Callus Line , Cory Ray Brouwer

Retrospective Theses and Dissertations

Matrix attachment regions (MARs) are DNA sequences that bind non-histone proteins in the chromatin scaffold and define discrete loops of DNA containing expressed genes in vivo. I have been studying the effects of flanking transgenes with MARs on transgene expression levels in BMS maize callus. Three MAR elements, two from maize (Adhl 5' MAR and Mhal 5' MAR) and one from yeast (ARS1), have very different effects on transgene expression that bear no relation to their affinity for the nuclear matrix in vitro. The main effect of MARs is to prevent silencing of some (but not all) transgenes, at least ...


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 ...


Potato Lipoxygenase Genes: Their Role In Tuber Formation And Defense Responses Against Pathogens , Mikhailo V. Kolomiets Jan 1998

Potato Lipoxygenase Genes: Their Role In Tuber Formation And Defense Responses Against Pathogens , Mikhailo V. Kolomiets

Retrospective Theses and Dissertations

Lipoxygenase (LOX) is involved in the synthesis of jasmonic acid, methyl jasmonate, traumatin, and C-6 volatile compounds that serve hormone-like regulatory and defense-related roles in plants. To study possible lipoxygenase involvement in potato tuberization and defense responses against pests, we have isolated, sequenced, and characterized three lipoxygenase cDNA clones that represent distinct LOX genes. Two of these genes, designated POTLX-1 and POTLX-2, have been isolated from an early tuber cDNA library. Northern hybridization studies indicated that accumulation of POTLX-1 and POTLX-2 mRNA was specific to developing tubers and roots and correlated positively with tuber growth. Hormonal treatment, pathogen infection, or ...


Biophysical Studies Of Catalytic And Starch Binding Domains Of Wild-Type And Mutant Glucoamylases From Aspergillus Awamori , Saber Malek Abdullah Khan Jan 1998

Biophysical Studies Of Catalytic And Starch Binding Domains Of Wild-Type And Mutant Glucoamylases From Aspergillus Awamori , Saber Malek Abdullah Khan

Retrospective Theses and Dissertations

Aspergillus awamori catalytic and starch binding domains were prepared, purified and characterized. Sedimentation equilibrium experiments and MALDI-TOF spectra reveals that GA470 and SBD contains ~12% and 5% carbohydrate, respectively. Temperature denaturation experiments indicate that catalytic domain unfolds irreversibly whereas that of SBD is reversible with DeltaH of ~410 and 71 kcal/mol, respectively, and T m of 60.9° and 51.3°C, respectively. Analysis of scan rate dependency data suggest that the thermal unfolding of GA470 was partially under kinetic control and do not follow a single two-step model. Comparison of Tm of isolated and intact GA470 and SBD ...


The Role Of Pit1 In The Putative Quantitative Trait Loci Region On Pig Chromosome 13 , Tun-Ping Yu Jan 1998

The Role Of Pit1 In The Putative Quantitative Trait Loci Region On Pig Chromosome 13 , Tun-Ping Yu

Retrospective Theses and Dissertations

PIT1 is an essential regulatory gene of growth hormone (GH), prolactin (PRL) and thyrotropin beta subunit. Previously, PIT1 polymorphisms and the chromosomal region near PIT1 in multiple pig populations is significantly associated with fatness and growth quantitative trait loci (QTLs) on pig chromosome 13. The purpose of this study is to confirm these previous results and clarify the role of the PIT1 gene in the putative QTL region;Cloning of the full length PIT1 cDNA was completed. The pig PIT1 cDNA and its deduced amino acids have approximately 90% and 95% sequence similarity respectively with the PIT1 cDNA and amino ...