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Biochemistry, Biophysics, and Structural Biology

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Articles 11971 - 12000 of 13229

Full-Text Articles in Life Sciences

Presented Antigen From Damaged Pancreatic Beta Cells Activates Autoreactive T Cells In Virus-Mediated Autoimmune Diabetes., Marc S. Horwitz, Alex Ilic, Cody Fine, Enrique Rodriguez, Nora Sarvetnick Jan 2002

Presented Antigen From Damaged Pancreatic Beta Cells Activates Autoreactive T Cells In Virus-Mediated Autoimmune Diabetes., Marc S. Horwitz, Alex Ilic, Cody Fine, Enrique Rodriguez, Nora Sarvetnick

Journal Articles: Regenerative Medicine

The induction of autoimmunity by viruses has been attributed to numerous mechanisms. In mice, coxsackievirus B4 (CB4) induces insulin-dependent diabetes mellitus (IDDM) resembling the final step of disease progression in humans. The immune response following the viral insult clearly precipitates IDDM. However, the molecular pathway between viral infection and the subsequent activation of T cells specific for islet antigen has not been elucidated. These T cells could become activated through exposure to sequestered antigens released by damaged beta cells, or they could have responded to factors secreted by the inflammatory response itself. To distinguish between these possibilities, we treated mice …

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Role Of Bcl-2 Family Members In Caspase-Independent Apoptosis Due To Chlamydia Infection, Jean-Luc Perfettini, John C. Reed, Nicole Israel, Jean-Claude Martinou, Alice Dautry-Varsat, David M. Ojcius Jan 2002

Role Of Bcl-2 Family Members In Caspase-Independent Apoptosis Due To Chlamydia Infection, Jean-Luc Perfettini, John C. Reed, Nicole Israel, Jean-Claude Martinou, Alice Dautry-Varsat, David M. Ojcius

All Dugoni School of Dentistry Faculty Articles

Infection with an obligate intracellular bacterium, the Chlamydia trachomatis lymphogranuloma venereum (LGV/L2) strain or the guinea pig inclusion conjunctivitis serovar of Chlamydia psittaci, leads to apoptosis of host cells. The apoptosis is not affected by a broad-spectrum caspase inhibitor, and caspase-3 is not activated in infected cells, suggesting that apoptosis mediated by these two strains of Chlamydia is independent of known caspases. Overexpression of the proapoptotic Bcl-2 family member, Bax, was previously shown to induce caspase-independent apoptosis, and we find that Bax is activated and translocates from the cytosol to the mitochondria in C. psittaci-infected cells. C. psittaci-induced apoptosis is …

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Influence Of Protein Tyrosine Kinases On Cell Volume Change-Induced Taurine Release, Herminia Pasantes-Morales, Rodrigo Franco Jan 2002

Influence Of Protein Tyrosine Kinases On Cell Volume Change-Induced Taurine Release, Herminia Pasantes-Morales, Rodrigo Franco

School of Veterinary and Biomedical Sciences: Faculty Publications

Taurine efflux occurs in association with cell swelling in both hyposmotic and isosmotic conditions and during cell shrinkage in apoptotic death. Release occurs through a leak pathway, is largely Ca2+-independent and is sensitive to Cl– channel blockers. Taurine efflux elicited by hyposmolarity is reduced or suppressed by tyrosine kinase blockers and increased by tyrosine phosphatase inhibitors. The specific kinases involved are still unknown and may be different in the various cell types. Non-receptor and scr-related protein kinases have been identified in some cells as elements that directly phosphorylate the taurine efflux pathway. Possible tyrosine kinase targets are …

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Kinetic Properties Of Bifunctional 6-Phosphofructo-2-Kinase/Fructose-2,6-Bisphosphatase From Spinach Leaves, Jennifer E. Markham, Nicholas J. Kruger Jan 2002

Kinetic Properties Of Bifunctional 6-Phosphofructo-2-Kinase/Fructose-2,6-Bisphosphatase From Spinach Leaves, Jennifer E. Markham, Nicholas J. Kruger

Department of Biochemistry: Faculty Publications

A cDNA encoding 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase was isolated from a Spinacia oleracea leaf library and used to ex­press a recombinant enzyme in Escherichia coli and Spodoptera frugiperda cells. The insoluble protein expressed in E. coli was purified and used to raise antibodies. Western blot analysis of a protein extract from spinach leaf showed a single band of 90.8 kDa. Soluble protein was purified to homogeneity from S. frugiperda cells infected with recombinant baculovirus harboring the isolated cDNA. The soluble protein had a molecular mass of 320 kDa, estimated by gel filtration chromatography, and a subunit size of 90.8 kDa. The purified pro­tein …

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Identification And Analysis Of A Conserved Immunoglobulin E-Binding Epitope In Soybean G1a And G2a And Peanut Ara H 3 Glycinins, Ping Ziang, Tom A. Beardslee, Michael G. Zeece, John P. Markwell, Gautam Sarath Jan 2002

Identification And Analysis Of A Conserved Immunoglobulin E-Binding Epitope In Soybean G1a And G2a And Peanut Ara H 3 Glycinins, Ping Ziang, Tom A. Beardslee, Michael G. Zeece, John P. Markwell, Gautam Sarath

Gautam Sarath Publications

To identify conserved immunoglobulin E (IgE)-binding epitopes among legume glycinins, we utilized recombinant soybean G2a and G2a-derived polypeptide fragments.

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Stat6 Mediates Interleukin-4 Growth Inhibition In Human Breast Cancer Cells, Jennifer L. Gooch, B. Christy, D. Yee Jan 2002

Stat6 Mediates Interleukin-4 Growth Inhibition In Human Breast Cancer Cells, Jennifer L. Gooch, B. Christy, D. Yee

PCOM Scholarly Works

In addition to acting as a hematopoietic growth factor, interleukin-4 (IL-4) inhibits growth of some transformed cells in vitro and in vivo. In this study, we show that insulin receptor substrate (IRS)-1, IRS-2, and signal transducer and activator of transcription 6 (STAT6) are phosphorylated following IL-4 treatment in MCF-7 breast cancer cells. STAT6 DNA binding is enhanced by IL-4 treatment. STAT6 activation occurs even after IRS-1 depletion, suggesting the two pathways are independent. To examine the role of STAT6 in IL-4-mediated growth inhibition and apoptosis, a full-length STAT6 cDNA was transfected into MCF-7 cells. Transient overexpression of STAT6 resulted in …

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Development Of A Chromatographic Method For The Analysis Of Carbohydrates In Posidonia Coriacea In Artificial Cultures, Olivia J. Oldfield Jan 2002

Development Of A Chromatographic Method For The Analysis Of Carbohydrates In Posidonia Coriacea In Artificial Cultures, Olivia J. Oldfield

Theses : Honours

Carbohydrates in P. coriacea leaves were analysed to determine if, when in artificial culture, they were unable to replenish their carbohydrate stores once the seed starch reserve was consumed. While no evidence was found to suggest that this was happening, other findings were made. Soluble carbohydrates determined in P. coriacea were sucrose, fructose, glucose, trehalose, myo-inositol and mannitol. However, mannitol was only found in in situ plants sampled in June. This may be due to high epiphyte coverage elevating plant stress and therefore mannitol levels. P. coriacea grown in tissue culture has soluble carbohydrate levels up to 20-fold higher than …

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Characterization Of An Acyl-Coa Thioesterase That Functions As A Major Regulator Of Peroxisomal Lipid Metabolism, Mary Hunt, Karianne Solaas, Bengt F. Kase, Stefan E H Alexson Jan 2002

Characterization Of An Acyl-Coa Thioesterase That Functions As A Major Regulator Of Peroxisomal Lipid Metabolism, Mary Hunt, Karianne Solaas, Bengt F. Kase, Stefan E H Alexson

Articles

Peroxisomes function in b-oxidation of very long- and long-chain fatty acids, dicarboxylic fatty acids, bile acid intermediates, prostaglandins, leukotrienes, thromboxanes, pristanic acid and xenobiotic carboxylic acids. These lipids are mainly chain-shortened for excretion as the carboxylic acids or transported to mitochondria for further metabolism. Several of these carboxylic acids are slowly oxidized and may therefore sequester coenzyme A (CoASH). To prevent CoASH sequestration and to facilitate excretion of chain-shortened carboxylic acids, acyl-CoA thioesterases, which catalyze the hydrolysis of acyl-CoAs to the free acid and CoASH, may play important roles. We have here cloned and characterized a peroxisomal acyl-CoA thioesterase from …

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Impact Of Sea Grass Density On Carbonate Dissolution In Bahamian Sediments, David J. Burdige, Richard C. Zimmerman Jan 2002

Impact Of Sea Grass Density On Carbonate Dissolution In Bahamian Sediments, David J. Burdige, Richard C. Zimmerman

OES Faculty Publications

Carbonate dissolution has been widely observed in shallow water tropical sediments. However, sediment budgets C have generally not been closed with respect to the amount of acid required to produce the observed carbonate dissolution. Recently it has been suggested that enhanced oxygen transport into sediments through the roots and rhizomes of sea grasses might play a role in resolving this mass balance problem. We conducted studies of sea grass-carbonate sediment interactions around Lee Stocking Island, Exuma Islands, Bahamas to further examine this problem. Our studies showed that alkalinity, total dissolved inorganic carbon (ΣCO2) and Ca2+ increased with …

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Behavioral And Reproductive Aspects Of Captive Maxwell's Duiker (Cephalophus Mawellii) Husbandry, Janet Mcneill Mackinnon Jan 2002

Behavioral And Reproductive Aspects Of Captive Maxwell's Duiker (Cephalophus Mawellii) Husbandry, Janet Mcneill Mackinnon

College of Graduate Studies: Theses & Dissertations (1964–2006)

Female Maxwell's duikers (Cephalophus maxwellii) were studied at the Wildlife Survival Center on St. Catherine's Island, Georgia. The objectives were to quantify the effects of housing on activity budgets and progesterone cycling. Four animals were studied across two housing situations: housed individually versus housed in a grouped setting. Behavioral observations revealed no significant change in access to resources, rumination, or repetitive behaviors, once animals were housed together. Fecal samples were collected in order to determine levels of progesterone through radioimmunoassay (RIA). Fluctuations in progesterone levels revealed no clear estrous cycles. Animals showed less variability in progesterone levels and …

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Methods And Compositions For Protection Against Bovine Viral Diseases, Subramaniam Srikumaran Jan 2002

Methods And Compositions For Protection Against Bovine Viral Diseases, Subramaniam Srikumaran

School of Veterinary and Biomedical Sciences: Faculty Publications

The present invention relates to methods and compositions for eliciting an immune response against bovine viral epitopes. The methods comprise combining at least one heat shock protein with at least one bovine viral epitope to form a purified epitope/heat shock protein complex and administration of an immune system stimulating amount of the purified epitope/heat shock protein complex. The compositions comprise, a purified epitope/heat shock protein complex comprising at least one bovine viral epitope complexed with at least one heat shock protein, and a pharmaceutically acceptable carrier, diluent or excipient.

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Molecular Mechanisms Involved In Human Platelet Aggregation By Synergistic Interaction Of Platelet-Activating Factor And 5-Hydroxytryptamine, B H. Shah, H Rasheed, I H. Rahman, A H. Shariff, F L. Khan, H B. Rahman, S Hanif, S A. Saeed Dec 2001

Molecular Mechanisms Involved In Human Platelet Aggregation By Synergistic Interaction Of Platelet-Activating Factor And 5-Hydroxytryptamine, B H. Shah, H Rasheed, I H. Rahman, A H. Shariff, F L. Khan, H B. Rahman, S Hanif, S A. Saeed

Department of Biological & Biomedical Sciences

Our recent studies have shown that co-activation of Gq and Gi proteins by 5-hydroxytryptamine (5-HT) and adrenaline show synergism in human platelet aggregation. This study was conducted to examine the mechanism(s) of synergistic interaction of 5-HT and platelet activating factor (PAF) in human platelets. We show that PAF, but not 5-HT, increased platelet aggregation in a concentration-dependent manner. However, low concentrations of 5-HT (2 microM) potentiated platelet aggregation induced by subthreshold concentration of PAF (40 nM) indicating a synergistic interaction between the two agonists and this synergism was blocked by receptor antagonists to either 5-HT or PAF. 5-HT also potentiated …

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Aerobic Biodegradation Of Methyl Tert-Butyl Ether By Aquifer Bacteria From Leaking Underground Storage Tank Sites, S. R. Kane, H. R. Beller, T. C. Legler, C. J. Koester, Holly C. Pinkart, R. U. Halden, A. M. Happel Dec 2001

Aerobic Biodegradation Of Methyl Tert-Butyl Ether By Aquifer Bacteria From Leaking Underground Storage Tank Sites, S. R. Kane, H. R. Beller, T. C. Legler, C. J. Koester, Holly C. Pinkart, R. U. Halden, A. M. Happel

All Faculty Scholarship for the College of the Sciences

The potential for aerobic methyl tert-butyl ether (MTBE) degradation was investigated with microcosms containing aquifer sediment and groundwater from four MTBE-contaminated sites characterized by oxygen-limited in situ conditions. MTBE depletion was observed for sediments from two sites (e.g., 4.5 mg/liter degraded in 15 days after a 4-day lag period), whereas no consumption of MTBE was observed for sediments from the other sites after 75 days. For sediments in which MTBE was consumed, 43 to 54% of added [U-14C]MTBE was mineralized to14CO2. Molecular phylogenetic analyses of these sediments indicated the enrichment of species closely …

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Formation Of Multistranded Structures From The Self-Assembly Of G-Rich Dna Oligomers By Various Sequence And Environmental Influences, Bryan D. Vi Dec 2001

Formation Of Multistranded Structures From The Self-Assembly Of G-Rich Dna Oligomers By Various Sequence And Environmental Influences, Bryan D. Vi

Seton Hall University Dissertations and Theses (ETDs)

No abstract provided.

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Ultrasound Based Quantitative Motion Measurement Using Speckle Size Estimation, James D. Hamilton, Larry Y. L. Mo, Gregory R. Bashford Nov 2001

Ultrasound Based Quantitative Motion Measurement Using Speckle Size Estimation, James D. Hamilton, Larry Y. L. Mo, Gregory R. Bashford

Biomedical Imaging and Biosignal Analysis Laboratory

An ultrasound system determines the relative movement in a first direction (F1) of first matter, such as blood flow, and second matter, such as an artery wall, in a subject under study (S). A beam (B1) of ultrasound waves defining a plurality of beam positions (BP1 and BP2) and beam axes (A1 and A2) are moved in scan direction having components parallel to direction F1. First and second blocks of data representing the first and second matter, respectively, are generated. A processor (20) performs an estimation of speckle size on first data to obtain a first result, and performs analysis …

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Transitions In Histone Acetylation Reveal Boundaries Of Three Separately Regulated Neighboring Loci, Michael D. Litt, Melanie A. Simpson, Felix Recillas-Targa, Marie-Noelle Prioleau, Gary Felsenfeld Oct 2001

Transitions In Histone Acetylation Reveal Boundaries Of Three Separately Regulated Neighboring Loci, Michael D. Litt, Melanie A. Simpson, Felix Recillas-Targa, Marie-Noelle Prioleau, Gary Felsenfeld

Department of Biochemistry: Faculty Publications

We have studied developmentally regulated patterns of histone acetylation at high resolution across ~54 kb of DNA containing three independently regulated but neighboring genetic loci. These include a folate receptor gene, a 16 kb condensed chromatin region, the chicken β-globin domain and an adjacent olfactory receptor gene. Within these regions the relative levels of acetylation appear to fall into three classes. The condensed chromatin region maintains the lowest acetylation at every developmental stage. Genes that are inactive show similarly low levels, but activation results in a dramatic increase in acetylation. The highest levels of acetylation are seen at regulatory sites …

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Map Kinases In Cynomolgus Monkey Sperm Hyperactivation, Emily Nicole Haynes Oct 2001

Map Kinases In Cynomolgus Monkey Sperm Hyperactivation, Emily Nicole Haynes

Biological Sciences Theses & Dissertations

Mammalian sperm exhibit characteristic motility patterns, termed hyperactivated (HA) motility, associated with completion of capacitation. In cynomolgus monkey (Macaca fascicularis) sperm, this HA motility is dependent in vitro upon the addition of exogenous cyclic nucleotide mediators, caffeine and dibutyryl-cyclic adenosine monophosphate (dbcAMP). Previous reports have shown protein tyrosine phosphorylation to be an integral component of this caffeine- and cAMP-stimulated HA motility. This study investigated the involvement of the mitogen-activated protein (MAP) kinase-signaling cascade. Semen specimens were collected in Talp-HEPES medium from proven breeders via electroejaculation. After washing, sperm were incubated in the presence and absence of the MAP …

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Correlation Between Histone Lysine Methylation And Developmental Changes At The Chicken Β-Globin Locus, Michael D. Litt, Melanie A. Simpson, Miklos Gaszner, D. David Allis, Gary Felsenfeld Sep 2001

Correlation Between Histone Lysine Methylation And Developmental Changes At The Chicken Β-Globin Locus, Michael D. Litt, Melanie A. Simpson, Miklos Gaszner, D. David Allis, Gary Felsenfeld

Department of Biochemistry: Faculty Publications

Methylation of histones at specific residues plays an important role in transcriptional regulation. Chromatin immunoprecipitation of dimethylated lysine 9 on histone H3 across 53 kilobases of the chicken β-globin locus during erythropoiesis shows an almost complete anticorrelation between regions of elevated lysine 9 methylation and acetylation. Lysine 9 is methylated most over constitutive condensed chromatin and developmentally inactive globin genes. In contrast, lysine 4 methylation of histone H3 correlates with H3 acetylation. These results lead us to propose a mechanism by which the insulator in the β-globin locus can protect the globin genes from being silenced by adjacent condensed chromatin.

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Inferring And Testing Hypotheses Of Cladistic Character Dependence By Using Character Compatibility, F. Robin O’Keefe, Peter J. Wagner Sep 2001

Inferring And Testing Hypotheses Of Cladistic Character Dependence By Using Character Compatibility, F. Robin O’Keefe, Peter J. Wagner

Biological Sciences Faculty Research

The notion that two characters evolve independently is of interest for two reasons. First, theories of biological integration often predict that change in one character requires complementary change in another. Second, character independence is a basic assumption of most phylogenetic inference methods, and dependent characters might confound attempts at phylogenetic inference. Previously proposed tests of correlated character evolution require a model phylogeny and therefore assume that nonphylogenetic correlation has a negligible effect on initial tree construction. This paper develops “tree-free” methods for testing the independence of cladistic characters. These methods can test the character independence model as a hypothesis before …

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Identification And Characterization Of A New Mammalian Glutaredoxin (Thioltransferase), Grx2, Vadim N. Gladyshev, Aimin Liu, Sergey V. Novoselov, Konstantin Krysan, Qi-An Sun, Valentin M. Kryukov, Gregory V. Kryukov, Marjorie F. Lou Aug 2001

Identification And Characterization Of A New Mammalian Glutaredoxin (Thioltransferase), Grx2, Vadim N. Gladyshev, Aimin Liu, Sergey V. Novoselov, Konstantin Krysan, Qi-An Sun, Valentin M. Kryukov, Gregory V. Kryukov, Marjorie F. Lou

Vadim Gladyshev Publications

A thiol/disulfide oxidoreductase component of the GSH system, glutaredoxin (Grx), is involved in the reduction of GSH-based mixed disulfides and participates in a variety of cellular redox pathways. A single cytosolic Grx (Grx1) was previously described in mammals. We now report identification and characterization of a second mammalian Grx, designated Grx2. Grx2 exhibited 36% identity with Grx1 and had a disulfide active center containing the Cys-Ser-Tyr-Cys motif. Grx2 was encoded in the genomes of mammals and birds and expressed in a variety of cell types. The gene for human Grx2 consisted of four exons and three introns, spanned 10 kilobase …

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Selenium Metabolism In Drosophila, F. Javier Martin-Romero, Gregory V. Kryukov, Alexei V. Lobanov, Bradley A. Carlson, Byeong Jae Lee, Vadim N. Gladyshev, Dolph L. Hatfield Aug 2001

Selenium Metabolism In Drosophila, F. Javier Martin-Romero, Gregory V. Kryukov, Alexei V. Lobanov, Bradley A. Carlson, Byeong Jae Lee, Vadim N. Gladyshev, Dolph L. Hatfield

Vadim Gladyshev Publications

Selenocysteine is a rare amino acid in protein that is encoded by UGA with the requirement of a downstream mRNA stem-loop structure, the selenocysteine insertion sequence element. To detect selenoproteins in Drosophila, the entire genome was analyzed with a novel program that searches for selenocysteine insertion sequence elements, followed by selenoprotein gene signature analyses. This computational screen and subsequent metabolic labeling with 75Se and characterization of selenoprotein mRNA expression resulted in identification of three selenoproteins: selenophosphate synthetase 2 and novel G-rich and BthD selenoproteins that had no homology to known proteins. To assess a biological role for these …

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Problem-Based Learning Variant: Transition Phase For A Large Institution, I Khan, A Fareed Aug 2001

Problem-Based Learning Variant: Transition Phase For A Large Institution, I Khan, A Fareed

Department of Biological & Biomedical Sciences

Objective: To compare students' test scores and perceptions of problem-based learning (PBL) and lecture-based learning (LBL) by applying a PBL-variant.
Method: For the transition from LBL to PBL, PBL was varied for one discipline only and for a large group of students. Two hundred forty nine second year medical students were taught a topic of Biochemistry by the LBL method and then 141 of these were taught another topic by the PBL-variant. At the conclusion of each topic an MCQ test was given. One week later a 9 item questionnaire was given to the 50 students now attending classes to …

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Sir3-Dependent Assembly Of Supramolecular Chromatin Structures In Vitro, Philippe T. Georgel, Madeleine A. Palacios Debeer, Gregory Pietz, Catherine A. Fox, Jeffrey C. Hansen Jul 2001

Sir3-Dependent Assembly Of Supramolecular Chromatin Structures In Vitro, Philippe T. Georgel, Madeleine A. Palacios Debeer, Gregory Pietz, Catherine A. Fox, Jeffrey C. Hansen

Biological Sciences Faculty Research

Baculovirus-expressed recombinant Sir3p (rSir3p) has been purified to near homogeneity, and its binding to naked DNA, mononucleosomes, and nucleosomal arrays has been characterized in vitro. At stoichiometric levels rSir3p interacts with intact nucleosomal arrays, mononucleosomes, and naked DNA, as evidenced by formation of supershifted species on native agarose gels. Proteolytic removal of the core histone tail domains inhibits but does not completely abolish rSir3p binding to nucleosomal arrays. The linker DNA in the supershifted complexes remains freely accessible to restriction endonuclease digestion, suggesting that both the tail domains and nucleosomal DNA contribute to rSir3p–chromatin interactions. Together these data indicate …

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Intrasteric Inhibition Of Atp Binding Is Not Required To Prevent Unregulated Autophosphorylation Or Signaling By The Insulin Receptor, Mark Frankel, Ararat J. Ablooglu, Joseph W. Leone, Elena Rusinova, J. B. A. Ross, Robert L. Heinrikson, Ronald A. Kohanski Jul 2001

Intrasteric Inhibition Of Atp Binding Is Not Required To Prevent Unregulated Autophosphorylation Or Signaling By The Insulin Receptor, Mark Frankel, Ararat J. Ablooglu, Joseph W. Leone, Elena Rusinova, J. B. A. Ross, Robert L. Heinrikson, Ronald A. Kohanski

Chemistry and Biochemistry Faculty Publications

Receptor tyrosine kinases may use intrasteric inhibition to suppress autophosphorylation prior to growth factor stimulation. To test this hypothesis we made an Asp1161Ala mutant in the activation loop that relieved intrasteric inhibition of the unphosphorylated insulin receptor (IR) and its recombinant cytoplasmic kinase domain (IRKD) without affecting the activated state. Solution studies with the unphosphorylated mutant IRKD demonstrated conformational changes and greater catalytic efficiency from a 10-fold increase in kcat and a 15-fold-lower Km ATP although Km peptide was unchanged. Kinetic parameters of the autophosphorylated mutant and wild-type kinase domains were virtually identical. The Asp1161Ala mutation increased the …

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Unexpected Post-Translational Modifications And Novel Sequence-Structure Relationships Revealed By The Crystal Structure Of Chlamydomonas Reinhardtii Rubisco, T. C. Taylor, A. Backlund, R. J. Spreitzer, I. Andersson Jul 2001

Unexpected Post-Translational Modifications And Novel Sequence-Structure Relationships Revealed By The Crystal Structure Of Chlamydomonas Reinhardtii Rubisco, T. C. Taylor, A. Backlund, R. J. Spreitzer, I. Andersson

Department of Biochemistry: Faculty Publications

The crystal structure of Rubisco from Chlamydomonas reinhardtii has been solved to 1.4 Å resolution. In addition to clear electron density for the carbamate on lys-201, the active site magnesium ion and the inhibitor 2-CABP, there was unexpected but unambiguous electron density for further specific post-translational modification. The N-terminus of the mature small subunit is methylated. The large subunit contains two methylcysteine residues (256 & 369) and two hydroxyproline residues (104 & 151). The small subunit from Chlamydomonas shows a structure more similar to that of the higher green plants than that from other algae of known structure. An extensive …

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Can Negligible Levels Of Rubisco Activase, Be The Reason For Decreased Rubisco Activity Levels In Guard Cells?, S. Madhavan, P. Echtenkamp Jul 2001

Can Negligible Levels Of Rubisco Activase, Be The Reason For Decreased Rubisco Activity Levels In Guard Cells?, S. Madhavan, P. Echtenkamp

Department of Biochemistry: Faculty Publications

Rubisco in guard cell chloroplasts has been a subject of controversy for decades. Several studies have unequivocally confirmed not only the presence of Rubisco in guard cells but also found it to be catalytically active. Based on a cell basis, the amount of Rubisco in guard cells is suggested to be in the range of 0.6 to 1.4 % whereas its activity is reported to be in the range of 0.35 to 0.5%, of a mesophyll cell. This low activity may be due a) to a low Rubisco content, and/or, b) to either the absence or an inactive functional activation …

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Reversible Phosphorylation Of Photosynthetic Pep Carboxylase: Studies On C4-Leaf Pp2a And Recombinant Pepc-Kinase From Cam-Induced Mesembryanthemum Crystallinum, L. Dong, N. V. Ermolova, M. A. Cushman, T. Taybi, J. C. Cushman, Raymond Chollet Jul 2001

Reversible Phosphorylation Of Photosynthetic Pep Carboxylase: Studies On C4-Leaf Pp2a And Recombinant Pepc-Kinase From Cam-Induced Mesembryanthemum Crystallinum, L. Dong, N. V. Ermolova, M. A. Cushman, T. Taybi, J. C. Cushman, Raymond Chollet

Department of Biochemistry: Faculty Publications

The activity and allosteric properties of plant PEPC are controlled posttranslationally by specific reversible phosphorylation of a strictly conserved Ser residue near the N-terminus. This up/down-modulation is catalyzed by a transcriptionally regulated, seemingly dedicated Ser/Thr kinase (PpcK) and an opposing Ser/Thr phosphatase (PP2A). We have now partially purified and characterized the native form of this largely “neglected” PP2A from maize leaves using various chromatographic and affinity matrices, and C4 [32P]PEPC as substrate (Dong et al., 2001, Planta [in press]). The results indicate that the C4-leaf holoenzyme is analogous to yeast and mammalian PP2As in regards …

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Positive Regulation Of Pka On Human Gonadotropin-Releasing Hormone (Hgnrh) Gene Expression In Human Placental Jeg-3 Cells, Zhaoyang Wen Jul 2001

Positive Regulation Of Pka On Human Gonadotropin-Releasing Hormone (Hgnrh) Gene Expression In Human Placental Jeg-3 Cells, Zhaoyang Wen

Chemistry & Biochemistry Theses & Dissertations

Using the human placental choriocarcinoma JEG-3 cell line as an in vitro human placental model, we studied the mechanisms of the PKA positive regulation of the hGnRH gene expression in the human placenta. Studies in JEG3 cells showed that through the PKA catalytic subunit a, human GnRH upstream promoter activity was stimulated by PKA signaling pathway in a cAMP dependent mechanism. The sequence between —202 (Afl II) and —554 (BamH I) base pair in the human GnRH upstream promoter region appeared to be responsible for the PKA positive regulation of the gene expression. Furthermore, Western blot analysis demonstrated the involvement …

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Interactions Among Murine Cytomegalovirus Us22 Family Gene Products That Influence Viral Pathogenesis, Zaruhi Karabekian Jul 2001

Interactions Among Murine Cytomegalovirus Us22 Family Gene Products That Influence Viral Pathogenesis, Zaruhi Karabekian

Theses and Dissertations in Biomedical Sciences

Cytomegalovirus (CMV) is a complex, ubiquitous herpesvirus that is characterized by acute, chronic, and latent infections. Monocytes-macrophages are the key target cell type involved in pathogenesis, which is most effectively studied using the murine model of CMV infection. Previously three murine CMV (MCMV) genes (M139, M140, and M141) were identified to regulate viral expression in cultured macrophages and in mice. These genes are members of the US22 gene family with respect to HCMV homology. There is no function assigned to the proteins encoded by these genes. However, deletion of M139, M140, and M141 significantly curtails growth of MCMV in macrophages …

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Regulation Of The Hcmv Ul98 Promoter By Cooperation Of The Cyclic Amp Response Element And Gamma Interferon Response Element, Tabmitha Patricia Young Jervey Jul 2001

Regulation Of The Hcmv Ul98 Promoter By Cooperation Of The Cyclic Amp Response Element And Gamma Interferon Response Element, Tabmitha Patricia Young Jervey

Theses and Dissertations in Biomedical Sciences

The HCMV UL98 early alkaline exonuclease gene promoter was examined to determine the DNA sequences as well as viral and/or cellular proteins functional in the regulation of this early gene. To assess promoter activation, UL98 promoter sequences were first cloned upstream of the chloramphenicol acetyltransferase (CAT) reporter gene and cotransfected with expression plasmids which express the HCMV major immediate early (IE) proteins 1E72 and 1E86. To more specifically determine the importance of individual cis-acting elements in UL98 promoter activation, the promoter region underwent mutagenesis to delete or alter sequences. The variant promoters were again cloned into a reporter-CAT construct and …

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