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

Use Of Pyrimidine Pathway To Produce Mutant Plants That Fail To Respond To Wound Induction , Lan Zhou Jan 1997

Use Of Pyrimidine Pathway To Produce Mutant Plants That Fail To Respond To Wound Induction , Lan Zhou

Retrospective Theses and Dissertations

To understand how proteinase inhibitor genes, as a part of plant defense system, are activated following wounding, we have developed a molecular genetic approach to directly select for mutants blocked in wound response in Arabidopsis thaliana. The wound-inducible promoter from the potato Proteinase Inhibitor 11 gene (pin2) was linked to a bacterial negative marker gene codA encoding for cytosine deaminase and transformed into Arabidopsis thaliana. The cytosine deaminase activity was detected in the leaves of the transgenic plants induced by sucrose, ABA, methyl jasmonate and mechanical wounding. Methyl jasmonate was the best for the pin2 induction in the seedlings among ...


Gene Expression Studies Of Murine Pregnancy Associated Granulated Metrial Gland And Decidual Cells , Melissa Phillips Allen Jan 1997

Gene Expression Studies Of Murine Pregnancy Associated Granulated Metrial Gland And Decidual Cells , Melissa Phillips Allen

Retrospective Theses and Dissertations

During pregnancy in viviparous mammals, the maternal decidua develops between the embryo and the uterine endometrium. This dissertation describes research on two different cell types present within the rodent decidua during pregnancy, namely, granulated metrial gland (GMG) cells and decidual cells;GMG cells are natural killer cells that proliferate and differentiate within the murine uterus during pregnancy. Their differentiation is associated with the accumulation of cytolytic mediators within cytoplasmic granules. The signaling mechanisms required for GMG cell differentiation, however, are largely unknown. In this study, expression of the genes coding for granzymes D, E, F, and G (granzymes D-G) was ...


Structure-Function Relationships In Porcine Fructose-1, 6-Bisphosphatase , Rulin Zhang Jan 1997

Structure-Function Relationships In Porcine Fructose-1, 6-Bisphosphatase , Rulin Zhang

Retrospective Theses and Dissertations

Fructose-1,6-bisphosphatase (FBPase) plays a crucial role in the regulation of gluconeogenesis. It is a homotetramer with a subunit molecular mass of 37 kDa. Each subunit has one substrate and three metal binding sites. Site-directed mutagenesis were carried out to replace amino acid residues which are thought to play important roles in structure integrity and functioning of the enzyme. Particular emphasis was placed on residues in the substrate and metal binding sites as well as the residues at the C1C2 (C3C4) interface. The mutant and wild-type FBPases were purified to homogeneity and characterized by initial-rate kinetics and circular dichroism spectrometry ...


Suppressor Analysis Of The Protein Kinase Elm1p, An Enzyme Involved In The Regulation Of Yeast Morphology , Nicholas Patrick Edgington Jan 1997

Suppressor Analysis Of The Protein Kinase Elm1p, An Enzyme Involved In The Regulation Of Yeast Morphology , Nicholas Patrick Edgington

Retrospective Theses and Dissertations

Saccharomyces cerevisiae is an ascomycete that has several developmental options, with concomitant morphological changes, that depend on cell type and nutrient status. In response to these signals, vegetative Saccharomyces cerevisiae cells assume one of two distinct morphologies, the yeast form or the filamentous form. Molecules affecting this morphogenetic response were identified by analyzing transposon-induced or spontaneous suppressor mutations that restore yeast form growth to a strain that constitutively exhibits filamentous form characteristics owing to mutation of the protein kinase Elm1p. One transposon-tagged mutation was isolated and is allelic to the negative regulatory subunit Bcy1p, thus activation of cAMP dependent protein ...


Structure And Function Of Escherichia Coli Valine Transfer Rna In Aminoacylation And Ternary Complex Formation , Jack Chia-Hsiang Liu Jan 1997

Structure And Function Of Escherichia Coli Valine Transfer Rna In Aminoacylation And Ternary Complex Formation , Jack Chia-Hsiang Liu

Retrospective Theses and Dissertations

The relationship of E. coli tRNA Val structure to its function in the aminoacylation reaction and the later steps of polypeptide synthesis was investigated. Steady-state kinetic studies of the aminoacylation of invitro transcribed tRNA Val variants have shown that nucleotides, A35, C36, A73, and G20, are important for the specific recognition of E. coli tRNA Val by valyl-tRNA synthetase (ValRS). Identity swap experiments, testing the efficiency of this "recognition nucleotide set" in converting yeast tRNA Phe and E. coli tRNA Phe into caline acceptors, confirm the importance of the recognition nucleotide set. In addition, a minor recognition nucleotide, G45, was ...


Study Of Avian Acyl-Coa Cholesterol Acyltransferase , Donghui Cheng Jan 1997

Study Of Avian Acyl-Coa Cholesterol Acyltransferase , Donghui Cheng

Retrospective Theses and Dissertations

Acyl-CoA Cholesterol Acyltransferase (ACAT) (EC.2.3.1.26) catalyzes intracellular esterification of cholesterol with long chain fatty acyl-CoA. ACAT is an integral membrane protein of the endoplasmic reticulum membrane and plays a very important role in intracellular cholesterol homeostasis. Activity of ACAT is important for the production and secretion of lipoproteins and for intestinal absorption of dietary cholesterol. The involvement of ACAT activity in the pathogenesis of atherosclerosis and its related heart diseases leads to an extensive effort from both the pharmaceutical industry and the basic research community to study this protein and its catalytic mechanism. ACAT from yolk ...


Identification Of Mouse Sip24/24p3 As A New Acute Phase Protein And Study Of Its Expression , Quansheng Liu Jan 1996

Identification Of Mouse Sip24/24p3 As A New Acute Phase Protein And Study Of Its Expression , Quansheng Liu

Retrospective Theses and Dissertations

Mouse SIP24 was originally discovered as a 24 k Da inducible protein secreted from quiescent Balb/c 3T3 fibroblast cells. Based on the analysis of peptide sequencing results and Western blot studies, SIP24 was identified as identical to the mouse protein encoded by 24P3 and is thus referred to as SIP24/24P3 in this thesis. SIP24/24P3 is a member of the lipocalin protein family, and its human homolog NGAL (neutrophil gelatinase associated lipocalin) has been reported to bind the chemotactic factor, fMLP (N-formylmethionyl-leucyl-phenylalanine);Studies were carried out to test the hypothesis that SIP24/24P3 is an acute phase protein ...


The Structure And Function Of Human Brain Hexokinase , Chenbo Zeng Jan 1996

The Structure And Function Of Human Brain Hexokinase , Chenbo Zeng

Retrospective Theses and Dissertations

An ATP binding site model for human brain hexokinase was established based on the similarity of the ATP-binding domains among actin, heat shock protein, glycerol kinase and brain hexokinase. Site directed mutagenesis was performed on the residues in the putative ATP-binding site in order to substantiate or refute the proposed model. The k cat values decreased 1000- and 200-fold for the Asp532Lys and Asp532Glu mutants, 114- and 12-fold for the Arg539Ile and Arg539Lys mutants, 2000- and 2-fold for the Thr680Val and Thr680Ser mutants, respectively. It is suggested that these residues are important for catalysis by either keeping the [gamma]-phosphoryl ...


Studies On The Structure-Function Relationships And Regulation Mechanisms Of Escherichia Coli Adenylosuccinate Synthetase , Wenyan Wang Jan 1996

Studies On The Structure-Function Relationships And Regulation Mechanisms Of Escherichia Coli Adenylosuccinate Synthetase , Wenyan Wang

Retrospective Theses and Dissertations

Molecular biological, biochemical, and biophysical techniques were utilized to explore structure-function relationship of Escherichia coli adenylosuccinate synthetase. For the first time, residues Arg303, Arg304 and Arg305 were implicated as the determinants in the recognition and binding of substrate L-aspartate. Replacing Arg305 with leucine resulted in over a 100-fold decrease in kcat, suggesting a possible role of Arg305 in catalysis. pH dependent kinetic studies indicated that the side chain of Gln224 is not only involved in recognition of IMP, but also in stabiling the intermediate 6-phosphoryl-IMP. Substitution of the side chain amide with a carboxylate group resulted in loss of catalytic ...


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 ...


X-Ray Crystallographic Studies Of The Nucleotide Binding Sites On Adenylosuccinate Synthetase From Esherichia Coli , Bradley Wayne Poland Jan 1996

X-Ray Crystallographic Studies Of The Nucleotide Binding Sites On Adenylosuccinate Synthetase From Esherichia Coli , Bradley Wayne Poland

Retrospective Theses and Dissertations

The crystal structures of unligated adenylosuccinate synthetase from Esherichia coli in the space groups P21 and P212121 have been refined to R-factors of 0.199 and 0.206 against 2.0 and 2.5A data, respectively. The dominant structural motif of the synthetase monomer is a central 10 stranded [beta]-sheet composed of 9 parallel strands and a 10th antiparallel strand. Four subdomains extend off of this [beta]-sheet and contribute loops of residues which are disordered. The dimer interface involves two nearly-independent regions. A pair of helicea (H4 & H5) interacting with their symmetry equivalent mates defines the first region. The second region involves structural elements which connect strands of the central [beta]-sheet. Residues in the putative IMP binding site are also located at or near the dimer interface;The P212121 crystal form allows gradual infusion of guanosine triphosphate ribonucleotides ...


Study Of The Structural Requirements Of E Coli Valine Transfer Rna In Aminoacylation And Protein Synthesis , Mingsong Liu Jan 1995

Study Of The Structural Requirements Of E Coli Valine Transfer Rna In Aminoacylation And Protein Synthesis , Mingsong Liu

Retrospective Theses and Dissertations

The structural requirements for the function of the 3[superscript]' CCA end of E. coli valine transfer RNA in aminoacylation and protein synthesis have been investigated, by studying the activities of 3[superscript]' end tRNA[superscript] Val variants in these processes. These studies show that 3[superscript]' end tRNA[superscript] Val variants can be obtained which are functional in both aminoacylation and later steps of protein synthesis. Replacement of the 3[superscript]' terminal adenosine with either cytosine or uracil yields tRNAs that retain almost full aminoacylation activity (40-50% that of wild type tRNA[superscript] Val). The tRNA[superscript] Val variant ...


The Interaction Between Actin Filaments And The Cytoskeleton-Membrane Attachment Site Protein Talin , Jinwen Zhang Jan 1995

The Interaction Between Actin Filaments And The Cytoskeleton-Membrane Attachment Site Protein Talin , Jinwen Zhang

Retrospective Theses and Dissertations

Talin, a protein localized primarily in cell-matrix type adherens junctions, is involved in linking the cytoskeleton to the cell membrane. The major objectives of my study were to (1) determine the structural basis for the effect of pH and ionic strength on the direct talin-actin interaction, (2) examine the effects of other factors, such as specific phospholipids, on the talin-actin interaction, and (3) compare abilities of human platelet and avian smooth muscle talins to interact with actin. Negative staining results showed that at pH 6.4 and low ionic strength, talin extensively crosslinked actin filaments into both tight networks and ...


Aspects Of Protein Phosphatase Regulation , Jennifer Marie Imparl Radosevich Jan 1995

Aspects Of Protein Phosphatase Regulation , Jennifer Marie Imparl Radosevich

Retrospective Theses and Dissertations

Aspects of regulation of two protein phosphatases involved in signal tranduction are described in this dissertation. The first phosphatase, calcineurin, is involved in T-cell activation and is also regulated by Ca2+/calmodulin. Because most studies on the interaction between calmodulin and the enzymes which it activates have focused on the role of hydrophobic residues in the interaction, we have instead focused on the role of the positively charged arginine residue in calcineurin-calmodulin interaction. To this end, certain arginine residues in the C-terminal portion of calcineurin were converted to the neutral amino acid citrulline by the action of peptidylarginine deiminase. The ...


Biochemical And Molecular Biological Characterization Of Plant Acetyl-Coa Carboxylases , James J. Caffrey Jan 1995

Biochemical And Molecular Biological Characterization Of Plant Acetyl-Coa Carboxylases , James J. Caffrey

Retrospective Theses and Dissertations

Acetyl-CoA carboxylase is a biotin-containing enzyme which catalyzes the ATP-dependent carboxylation of acetyl-CoA to form malonyl-CoA. Plants are unique among organisms in that malonyl-CoA is utilized in both de novo fatty acid biosynthesis, and as an intermediate in a number of other plant primary and secondary metabolic pathways. Some of these metabolic pathways operate in different subcellular and cellular compartments. Therefore, plants have a mechanism to generate separate pools of malonyl-CoA. Understanding this mechanism has been the impetus for the research reported in this dissertation;Immunological and structural analyses of a 60 kDa biotinylated polypeptide (60kDBP) from carrot indicate that ...


Elm1p, A Protein Kinase That Regulates Cell Morphology In Saccharomyces Cerevisiae , Carla Marie Koehler Jan 1995

Elm1p, A Protein Kinase That Regulates Cell Morphology In Saccharomyces Cerevisiae , Carla Marie Koehler

Retrospective Theses and Dissertations

Saccharomyces cerevisiae is a pleimorphic ascomycete, capable of growing in the yeast form or the pseudohyphal form. The pseudohyphal form is characterized by elongated cells that possess a unipolar budding pattern and grow in chains away from the center of the colony. This change in morphology is induced by nitrogen starvation in the presence of carbon. A collection of 14 elm (elongated morphology) mutants previously have been isolated that grow as pseudohyphae constitutively. Of these mutants, the product of the ELM1 gene was identified and coded for a novel protein kinase. From genetic analyses, ELM1 seemingly functioned downstream of STE7 ...


The Role(S) Of Arginine-Specific Mono(Adp-Ribosyl)Transferase In Skeletal Muscle Cells , Hui-Yu Huang Jan 1995

The Role(S) Of Arginine-Specific Mono(Adp-Ribosyl)Transferase In Skeletal Muscle Cells , Hui-Yu Huang

Retrospective Theses and Dissertations

The overall goal of this research project was to examine the biological function of arginine-specific mono(ADP-ribosyl) transferase in skeletal muscle cells. To better understand the function of this enzyme in skeletal muscle, the experimental approach to accomplish this goal consisted of two specific objectives. The first objective was to identify the protein substrates for this enzyme in myogenic cell cultures and cellular fractions. Embryonic chick primary muscle cell cultures were used as a working system for this purpose. In membrane fractions of 96-h myotube cultures incubated with [[superscript]32 P]NAD under conditions selected for mono(ADP-ribosyl)ation, proteins ...


Investigation Of The Gtp-Binding Consensus Sequences In Escherichia Coli Adenylosuccinate Synthetase And The Enzyme's Reaction Mechanism , Chulhun Kang Jan 1995

Investigation Of The Gtp-Binding Consensus Sequences In Escherichia Coli Adenylosuccinate Synthetase And The Enzyme's Reaction Mechanism , Chulhun Kang

Retrospective Theses and Dissertations

In this dissertation, on the basis of the similarities in sequence and structure between GTP-binding proteins and AMPSase, it was of interest to determine whether or not the GTP-binding consensus sequences have similar functions. It will be shown that the GTP-binding consensus sequences found in AMPSase play similar roles to those of the GTPase superfamily. The kinetic results show that Lys331 interacts with GTP through hydrophobic interactions between its linear side chain and the aromatic ring of the guanine base of GTP. Also, structural characterization of the G15V mutant using circular dichroism (CD) spectrometry, NMR spectroscopy, and spectrofluorometry indicated that ...


5-Fluoroorotic Acid-Selected Cell Lines And Regulation Of Ump Synthase Gene Expression In Tobacco Cells , Djoko Santoso Jan 1995

5-Fluoroorotic Acid-Selected Cell Lines And Regulation Of Ump Synthase Gene Expression In Tobacco Cells , Djoko Santoso

Retrospective Theses and Dissertations

Plant uridine-5'-monophosphate (UMP) synthase has been studied at both the biochemical and molecular levels. Using a purification procedure of salt precipitation coupled with a series of chromatography techniques, UMP synthase was purified to more than 2,000-fold from crude extracts of Cucurbita pepo L. As with UMP synthases from other higher eukaryotes, the UMP synthase of squash has both orotate phosphoribosyl transferase and orotidine-5'-monophosphate (OMP) decarboxylase activities. The molecular mass of the native UMP synthase was about 110 kDa and SDS-PAGE showed a subunit molecular mass of 50 kDa. The other biochemical properties of this UMP synthase are ...


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 ...


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 ...


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 ...


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 ...


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 ...


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 ...


Characterization Of [Beta]-Methylcrotonyl-Coa Carboxylase Of Tomato: A Newly Identified Biotin Enzyme In Plants , Xun Wang Jan 1993

Characterization Of [Beta]-Methylcrotonyl-Coa Carboxylase Of Tomato: A Newly Identified Biotin Enzyme In Plants , Xun Wang

Retrospective Theses and Dissertations

Biotin-containing enzymes catalyze critical reactions in diverse metabolic processes. In contrast to the extensive characterizations of biotin-containing enzymes from animal and microbial sources, little is known about these enzymes from plants. I have isolated and sequenced cDNA clones coding for the biotin-containing subunit [beta]-methylcrotonyl-CoA carboxylase (MCCase) from tomato, the first molecular cloning of this enzyme from any organism, and the first molecular cloning of a plant biotin-containing enzyme. Comparison of the deduced amino acid sequence from these clones with other biotin-containing enzymes suggests that the 78 kD subunit carries biotin carboxylase and biotin carboxyl carrier functions. I have shown ...


The Function Of Free Sulfhydryl Groups In The Catalytic Subunit Of Phosphorylase Kinase , Chiun-Jye Yuan Jan 1993

The Function Of Free Sulfhydryl Groups In The Catalytic Subunit Of Phosphorylase Kinase , Chiun-Jye Yuan

Retrospective Theses and Dissertations

Phosphorylase kinase, a serine/threonine type kinase, has been recently found to contain tyrosine kinase activity by phosphorylating angiotensin II. The tyrosine kinase activity of phosphorylase kinase requires Mn[superscript]2+. In the presence of saturable metal-nucleotide complex, MgATP, the serine kinase activity is inhibited by Mn[superscript]2+, while tyrosine kinase activity is activated. The tyrosine kinase activity in holoenzyme is Ca[superscript]2+-independent but can be regulated by autophosphorylation. One active site with two conformations is proposed; one favors seryl phosphorylation, and the second tyrosyl phosphorylation which is caused by the binding of second metal ion;The ...


Acceptor Reactions And Mechanism Of Leuconostoc Mesenteroides B-512fm Dextransucrase , Aziz Tanriseven Jan 1993

Acceptor Reactions And Mechanism Of Leuconostoc Mesenteroides B-512fm Dextransucrase , Aziz Tanriseven

Retrospective Theses and Dissertations

Although Hanes-Woolf plot showed that methyl [alpha]-D-glucopyranoside was an apparent competitive inhibitor for dextransucrase, a Michaelis-Menten plot using methyl [alpha]-D-glucopyranoside in the presence of high concentration of sucrose showed that it was not a real competitive inhibitor. We have also found that methyl 6-deoxy-[alpha]-D-glucopyranoside and methyl 6-deoxy-6-fluoro-[alpha]-D-glucopyranoside were weak inhibitors, whereas the corresponding sucrose analogues 6-deoxysucrose and 6-deoxy-6-fluorosucrose are very potent inhibitors for dextransucrase. From these findings, it is concluded that the acceptor, methyl [alpha]-D-glucopyranoside, does not compete with sucrose for the sucrose binding-sites and it binds at a separate acceptor binding-site;A ...


Molecular Cloning And Characterization Of 3-Methylcrotonyl-Coa Carboxylase From Soybean , Jianping Song Jan 1993

Molecular Cloning And Characterization Of 3-Methylcrotonyl-Coa Carboxylase From Soybean , Jianping Song

Retrospective Theses and Dissertations

A cDNA clone and genes coding for the 85 kDa biotin-containing polypeptide of soybean has been isolated and sequenced. This 85 kDa polypeptide has been identified as the biotin-containing subunit of 3-methylcrotonyl-CoA carboxylase (MCCase). This is the first plant gene coding for a biotin-containing enzyme to be cloned. It is also the first time that the primary sequence of the biotin-containing subunit of MCCase has been determined;The deduced amino acid sequence of the biotin-containing subunit of MCCase of soybean shows high homology with other known biotin-containing enzymes. Amino acid sequence homology between the soybean MCCase and other biotin enzymes ...


Genetic Characterization And Molecular Cloning Of Genes Involved In Kernel Development In Zea Mays , Michael John Scanlon Jan 1993

Genetic Characterization And Molecular Cloning Of Genes Involved In Kernel Development In Zea Mays , Michael John Scanlon

Retrospective Theses and Dissertations

This dissertation describes the genetic and molecular characterization of maize genes that are required for kernel development. Maize stocks in which the Robertson's Mutator (Mu) transposable element system are especially active were used to generate 75 mutations affecting kernel development. Sixty-four kernel mutations were located to chromosome arm, and 17 were placed to more precise locations on the maize genetic map. Viability tests of kernels homozygous for defective kernel (dek) mutations revealed numerous pleiotropic effects on plants obtained from mutant kernels. Fifteen putative Mutator-induced mutations tested negative for allelism to any known gene required for kernel development, and thus ...