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Biochemistry, Biophysics, and Structural Biology

1991

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Articles 1 - 30 of 44

Full-Text Articles in Life Sciences

The Effects Of Selenate, Molybdate And Chromate On The Triiodothyronine Induced Enzyme Activity And Mrna Level For Both Fatty Acid Synthase And Malic Enzyme, Yuan Zhu Dec 1991

The Effects Of Selenate, Molybdate And Chromate On The Triiodothyronine Induced Enzyme Activity And Mrna Level For Both Fatty Acid Synthase And Malic Enzyme, Yuan Zhu

Masters Theses

In chick embryo hepatocytes in culture, triiodothyronine (T3) stimulates enzyme activity, mRNA level and transcription rate for both fatty acid synthase (FAS) and malic enzyme (ME). Recent evidence has demonstrated the effects of selenate, molybdate and chromate on various physiological processes. Little information, however, is available on the effects of these metal ions on the T3- regulated gene expression for FAS and ME.

In chick embryo hepatocytes incubated in a chemically defined medium, addition of sodium selenate (20 μM) coincident with T3 almost completely inhibited the T3-induced stimulation of FAS and ME activity and accumulation of their respective mRNA's. Neither …


Using Xenon As A Heavy Atom For Determining Phases In Sperm Whale Metmyoglobin, Jacqueline Vitali, Arthur H. Robbins, Steven C. Almo, Robert F. Tilton Oct 1991

Using Xenon As A Heavy Atom For Determining Phases In Sperm Whale Metmyoglobin, Jacqueline Vitali, Arthur H. Robbins, Steven C. Almo, Robert F. Tilton

Physics Faculty Publications

Xenon gas can be used as a heavy atom for determining phases in a protein. We demonstrate that an interpretable electron density map can be obtained for sperm whale metmyoglobin from a single xenon derivative using iterative single isomorphous replacement with the anomalous scattering method.


High Performance Liquid Chromatographic Separation Of Different Types Of Collagen, Yongjoo Chung Oct 1991

High Performance Liquid Chromatographic Separation Of Different Types Of Collagen, Yongjoo Chung

Chemistry & Biochemistry Theses & Dissertations

The objective of this research was to develop a method for the separation of different types of collagen using a large pore size (100 nm) reversed-phase C-8 column. Three different types of collagen (type I, III, and V) were sufficiently separated on the column using a mobile phase containing water-acetonitrile-trifluoroacetic acid. Collagens found in each HPLC peak were identified using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) to assay the column effluents.

Trifluoroacetic acid (TFA) was used as an ion pair reagent. This compound improved the chromatographic profile for these proteins on a reversed-phase column. It was observed that with …


The Alpha-Adrenergic Stimulation Of Atrial Natriuretic Factor Expression In Cardiac Myocytes Requires Calcium Influx, Protein Kinase C, And Calmodulin-Regulated Pathways, C A. Sei, C E. Irons, A B. Sprenkle, P M. Mcdonough, J H. Brown, C C. Glembotski Aug 1991

The Alpha-Adrenergic Stimulation Of Atrial Natriuretic Factor Expression In Cardiac Myocytes Requires Calcium Influx, Protein Kinase C, And Calmodulin-Regulated Pathways, C A. Sei, C E. Irons, A B. Sprenkle, P M. Mcdonough, J H. Brown, C C. Glembotski

Amy Sprenkle

It has been shown recently that a-adrenergic agonists can stimulate atrial natriuretic factor (ANF) expression in ventricular cardiac myocytes; however, little is known about the intracellular signals mediating this activation. The present study focused on the potential roles of calcium-regulated kinases and calcium influx in the a-adrenergic stimulation of ANF gene expression in ventricular myocardial cell cultures. Myocardial cells maintained for 48 h in serumfree medium supplemented with phenylephrine (PE) possessed up to 15-fold higher levels of ANF peptide and ANF mRNA than control cells. The removal of PE, or the addition of nifedipine, resulted in a rapid decline in …


Expression Of Biologically Active Human Corticosteroid Binding Globulin By Insect Cells: Acquisition Of Function Requires Glycosylation And Transport, Jayasri Ghose-Dastidar, J. B. Alexander Ross, Reza Green Aug 1991

Expression Of Biologically Active Human Corticosteroid Binding Globulin By Insect Cells: Acquisition Of Function Requires Glycosylation And Transport, Jayasri Ghose-Dastidar, J. B. Alexander Ross, Reza Green

Chemistry and Biochemistry Faculty Publications

Human corticosteroid binding globulin (hCBG) is a 50- to 55-kDa serum glycoprotein that binds cortisol and progesterone with high affinity. To map the steroid-binding domain and to investigate the folding pathways of hCBG, we have established an expression system based on infection of insect cells with a recombinant baculovirus encoding hCBG. Infected Spodoptera frugiperda (Sf9) cells secrete immunoreactive hCBG at high levels (16-24 pmol per 106 cells per 40 h), and the recombinant protein binds cortisol with an affinity and specificity equivalent to that of human serum-derived hCBG. Thus, this system has the potential to provide large amounts of …


Characterization Of Two Temperature-Sensitive Mutants Of Escherichia Coli Exhibiting An Altered L22 Ribosomal Protein, Bonnie A. Burnette-Vick Aug 1991

Characterization Of Two Temperature-Sensitive Mutants Of Escherichia Coli Exhibiting An Altered L22 Ribosomal Protein, Bonnie A. Burnette-Vick

Electronic Theses and Dissertations

Analysis of E. coli strains SK1047 and SK1048 have shown them to be temperature-sensitive, protein-synthesis deficient. An alteration in ribosomal protein L22 was detected in both strains using two dimensional gel electrophoresis. Protein L22 was purified from both strains by reversed phase high performance liquid chromatography and from two dimensional electrophoretic gels. Purified ribosomal protein L22 was labeled by reductive methylation and used in 23S RNA binding assays with and without ribosomal protein L4. At the permissive temperature, protein L22 from SK1047 bound less efficiently than the control while protein L22 from SK1048 bound as efficiently as the control. At …


Action Of Heptaminol Hydrochloride On Contractile Properties In Frog Isolated Twitch Muscle Fibre, Bruno Allard, Vincent Jacquemont, Fouad Lemtiri-Chlieh, Bernard Pourrias, Oger Rougier Jul 1991

Action Of Heptaminol Hydrochloride On Contractile Properties In Frog Isolated Twitch Muscle Fibre, Bruno Allard, Vincent Jacquemont, Fouad Lemtiri-Chlieh, Bernard Pourrias, Oger Rougier

fouad Lemtiri-Chlieh

1 Heptaminol stopped or delayed the progressive decline in tension which characterizes the phenomenon of fatigue in frog isolated twitch muscle fibre. 2 Heptaminol had no action on the sodium, potassium and calcium voltage-dependent ionic conductances. 3 The hypothesis of an action via an internal alkalinization was tested by comparison with the action of NH4Cl. Both substances increased the tension. 4 The action of hepataminol was suppressed in sodium-free (TRIS) solution or in the presence of amiloride while the action of NH4Cl was always observed. 5 These results could be explained by a stimulation of the Na/H antiport by heptaminol.


Purification And Characterization Of The Prostate Cancer-Associated Antigen: 7e11-C5, Qi Feng Jul 1991

Purification And Characterization Of The Prostate Cancer-Associated Antigen: 7e11-C5, Qi Feng

Theses and Dissertations in Biomedical Sciences

A murine monoclonal antibody (MAb), 7E11-C5, recognizes a prostate organ-specific antigen. Under reducing conditions, the 7E11-C5 antigen exhibited major 100-Kd and minor 70-Kd bands, suggesting that the antigen comprises two peptide chains. The antigen was detected in pooled normal human seminal plasma, xenograft tissue extract of a prostate adenocarcinoma cell line, LNCaP, and tissue extracts of benign prostatic hyperplasia (BPH) and prostate carcinomas, but was not identified in any of the non-prostate tissue extracts tested. Antibodies of the three major prostate-associated antigens (prostatic acid phosphatase (PAP), prostate specific antigen (PSA) and prostate secretory protein (PSP)) were unable to block the …


Cytolytic And Ion Channel Forming Properties Of The N-Terminus Of Lymphocyte Perforin, David M. Ojcius, Pedro M. Persechini, Li-Mou Zheng, Paulo C. Notaroberto, Sandro C. Adeodato, John Ding-E. Young Jun 1991

Cytolytic And Ion Channel Forming Properties Of The N-Terminus Of Lymphocyte Perforin, David M. Ojcius, Pedro M. Persechini, Li-Mou Zheng, Paulo C. Notaroberto, Sandro C. Adeodato, John Ding-E. Young

All Dugoni School of Dentistry Faculty Articles

Perforin lyses cells by binding to the target cell membrane, where it polymerizes into large nonspecific pores. It is shown here that the first 34 amino acids of the N-terminal region of either human or murine perforin are soluble in aqueous medium and spontaneously insert into membranes. The N-terminal peptides lyse liposomes and nucleated cells, and they form ion channels in planar bilayers, some of which are comparable to those previously described for perforin. The lytic activity of the N-terminal domains does not require calcium, is independent of the lipid headgroup composition, and can be inhibited by heparin. Tumor cells …


Heterogeneity Of Methotrexate Binding In Human Colon Tumor Cells, M P. Iqbal, N Mehboobali, M A. Waqar, M Ahmed Jun 1991

Heterogeneity Of Methotrexate Binding In Human Colon Tumor Cells, M P. Iqbal, N Mehboobali, M A. Waqar, M Ahmed

Department of Biological & Biomedical Sciences

[3H]-methotrexate binding at pH 5.0 and pH 7.2 by the cytosol of tumor tissues and the surrounding normal areas of the gastrointestinal tract of patients suffering from colon or gastric cancer has been used to identify in these cells the presence of a binder of methotrexate having low-affinity for this drug in addition to the enzyme dihydrofolate reductase. Scatchard analysis of the [3H]-methotrexate binding data by a colon tumor sample also reveals that there are two binders of this drug present in the cytosol of these cells. The association constant (Kass) for one binder of methotrexate is = 5.6 x …


Molecular Genetics Of Endocrine Induced Regression Of Mouse Leydig Cell Tumors, Milton Rolando Drachenberg Jun 1991

Molecular Genetics Of Endocrine Induced Regression Of Mouse Leydig Cell Tumors, Milton Rolando Drachenberg

Loma Linda University Electronic Theses, Dissertations & Projects

Chronic estrogen treatment results in malignant Leydig cell tumor formation in genetically susceptible strains of mice. The hypothesis that the mechanism of estrogen induced carcinogenesis includes a gene amplification event was tested using this in vivo endocrine carcinogenesis model. High molecular weight DNA isolated from liver, hyperplastic chryptorchid testes, primary Leydig cell tumors and transplanted tumor lines progressing to estrogen nondependence for growth, was studied using Southern blot analysis and the in-gel renaturation technique to identify amplification of characterized and anonymous sequences. No consistent gene amplification event could be demonstrated either in carcinogenesis or tumor progression to an estrogen nondependent …


Aerotaxis In Halobacterium Halobium, Jemima Clara Lindbeck Jun 1991

Aerotaxis In Halobacterium Halobium, Jemima Clara Lindbeck

Loma Linda University Electronic Theses, Dissertations & Projects

Aerotaxis, previously studied in eubacteria was investigated in the archaebacterium Halobacterium halobium. A quantitative temporal assay for aerotaxis of H. halobium was developed using computer assisted motion analysis. Aerotaxis was most pronounced in early log phase cultures. Peak aerotaxis was found to coincide with peak respiration consistent with a model in which respiration is required for aerotaxis. In a spatial assay a mutant strain lacking the proton motive force (pmf)-generating pigments, bacteriorhodopsin (bR) and halorhodopsin (hR), exhibited enhanced aerotaxis bands relative to the bR+hR+ parent. The enhanced aerotaxis in the mutant cells was not due solely to …


Mouse Mast Cell Proteases: Induction, Molecular Cloning, And Characterization, Wei Chu May 1991

Mouse Mast Cell Proteases: Induction, Molecular Cloning, And Characterization, Wei Chu

Electronic Theses and Dissertations

Tryptase, a mast cell-specific serine protease with trypsin-like specificity, has been identified in a mouse mast cell line (ABFTL-6) based on it's enzymatic activity, inhibition properties, and cross-reactivity to a human mast cell tryptase antibody. The effects of fibroblast-conditioned medium and sodium butyrate on ABFTL-6 mast cell differentiation and tryptase expression have been examined. ABFTL-6 mouse mast cells undergo phenotypic changes upon culturing in media supplemented with fibroblast-conditioned media at 50% or 1 mM sodium butyrate. The induced cells increased in size, had larger and more metachromatic cytoplasmic granules, and increased their total cellular protein about four-fold. Tryptase activity increased …


Nitrogen Dioxide Reaction With Proteins: Evidence For Peptide Bond Cleavage At Lysine Residues, Darryl B. Hood May 1991

Nitrogen Dioxide Reaction With Proteins: Evidence For Peptide Bond Cleavage At Lysine Residues, Darryl B. Hood

Electronic Theses and Dissertations

Nitrogen dioxide (NO$\sb2$), an air pollutant produced by burning fossil fuels and a component of cigarette smoke, is thought to contribute to the pathogenesis of pulmonary diseases, such as emphysema. To gain information on the mechanism by which NO$\sb2$ damages the lung, in vitro exposures of $\alpha\sb1$-proteinase inhibitor ($\alpha\sb1$-PI), elastin, bovine serum albumin (BSA), human serum albumin (HSA) and synthetic poly-L-lysine were performed. A genetic deficiency of $\alpha\sb1$-PI predisposes humans to emphysema and NO$\sb2$ has been hypothesized to damage $\alpha\sb1$-PI, which would leave proteases such as human neutrophil elastase, (HNE) free to attack lung structural proteins. The ability of $\alpha\sb1$-PI …


Domains And Anomalous Adsorption Isotherms Of Dipalmitoylphosphatidylcholine Membranes And Lipophilic Ions: Pentachlorophenolate, Tetraphenylborate, And Dipicrylamine, Pavel Smejtek, S. Wang May 1991

Domains And Anomalous Adsorption Isotherms Of Dipalmitoylphosphatidylcholine Membranes And Lipophilic Ions: Pentachlorophenolate, Tetraphenylborate, And Dipicrylamine, Pavel Smejtek, S. Wang

Physics Faculty Publications and Presentations

Dipalmitoylphosphatidylcholine (DPPC) vesicles acquire negative surface charge on adsorption of negatively charged pentachlorophenolate (PCP-), and lipophilic ions tetraphenylborate (TPhB-), and dipicrylamine (DPA-). We have obtained (a) zeta-potential isotherms from the measurements of electrophoretic mobility of DPPC vesicles as a function of concentration of the adsorbing ions at different temperatures (25–42 degrees C), and (b) studied the effect of PCP- on gel-to-fluid phase transition by measuring the temperature dependence of zeta-potential at different PCP- concentrations. The zeta-potential isotherms of PCP- at 25, 32, and 34 degrees C correspond to adsorption to membrane in its gel phase. At 42 degrees C the …


Metabolism Of Arachidonate-Containing Phospholipid Molecular Species In The Murine Macrophage-Like Cell Line, P388d1, Crystal R. Waites May 1991

Metabolism Of Arachidonate-Containing Phospholipid Molecular Species In The Murine Macrophage-Like Cell Line, P388d1, Crystal R. Waites

Electronic Theses and Dissertations

Glycerophospholipids of mammalian cells exist as chemically diverse structures with various fatty acids at the sn-1 and sn-2 positions. Arachidonic acid, a polyunsaturated fatty acid, which may be converted to biologically active eicosanoids such as prostaglandins, thromboxanes, and leukotrienes, is found predominantly in the sn-2 position of glycerophospholipids. The purpose of this study was to examine, at the level of the individual molecular species, the incorporation of arachidonate into phospholipids and its release from phospholipids during stimulation. In this way, the specificity of the enzymes controlling arachidonate metabolism could be examined in order to clarify the processes that control the …


The Study Of Natural Product(S) From Opsanus Tau (Linnaeus), The Oyster Toadfish, Miki Taira Apr 1991

The Study Of Natural Product(S) From Opsanus Tau (Linnaeus), The Oyster Toadfish, Miki Taira

Chemistry & Biochemistry Theses & Dissertations

Opsanus tau (Linnaeus), the Oyster toadfish, commonly inhabits the Chesapeake Bay. The Oyster toadfish has been categorized as a venomous and/or ichthyotoxic fish; however, chemical studies to substantiate these claims have not been forthcoming.

The oyster toadfish has dorsal and opercular spines which are believed to secrete a venom(s). Based on our findings, the oyster toadfish does not secrete venom(s) from these spines.

The oyster toadfish secretes large amounts of a mucus when it is irritated. 3-Octanone was believed to be the major ichthyotoxic component of the mucus from the oyster toadfish. Based on our investigation, 3-octanone is present only …


The Role Of Queuine Deficient Trna In Translational Control, Kathryn Lenore Hart Apr 1991

The Role Of Queuine Deficient Trna In Translational Control, Kathryn Lenore Hart

Theses and Dissertations in Biomedical Sciences

The purpose of this research was to study the effect of the level of tRNA modification with respect to queuine on translational efficiency. Transfer RNA from neoplastic cells is generally deficient with regard to certain hypermodified nucleosides found in normal cells. The hypothesis that was examined is whether or not the altered efficiency of translation can be correlated to the presence of queuine hypomodified tRNA. The loss of queuine in the anticodon may change the interaction of the tRNA's anticodon with its codon. Therefore, the translational complex may stall looking for a rare tRNA, or the stability of the complex …


A Biochemical Study Of Gossypol And Lactate Dehydrogenase X Binary Interactions, Patricia Brown Ravenell Apr 1991

A Biochemical Study Of Gossypol And Lactate Dehydrogenase X Binary Interactions, Patricia Brown Ravenell

Theses and Dissertations in Biomedical Sciences

The goal of this project was to study the mechanism of action of gossypol through its (a) binary interaction with native and trypsin digested lactate dehydrogenase-X (LD-X), a sperm-specific isozyme, and (b) its binding in vitro in primary cultures of spermatogenic cells. Mouse LD-X was cleaved with trypsin before and after treatment with gossypol. This was followed by high performance chromatography (HPLC) separation of the LD-X tryptic peptide fragments to observed alterations in separation patterns as indicators of intramolecular disturbance in the enzyme molecule. Definite alterations in peptide fragment peaks were observed in the presence of gossypol and suggest conformational …


Molecular Mechanism Of The Stimulation Of Alkaline Phosphatase Activity In Human Bone Cells By 1,25(Oh)2 D3, Eru Kyeyune-Nyombi Mar 1991

Molecular Mechanism Of The Stimulation Of Alkaline Phosphatase Activity In Human Bone Cells By 1,25(Oh)2 D3, Eru Kyeyune-Nyombi

Loma Linda University Electronic Theses, Dissertations & Projects

To facilitate this study an in vitro human model system was established that exhibited many aspects of normal osteoblasts. The human osteosarcoma cell line (TE85 cells) expressed a skeletal alkaline phosphatase activity (an accepted bone cell differentiation marker) which was stimulated by 1,25(OH)2D3 (a potent differentiating agent), under serum-free conditions in a dose-dependent, time-dependent, and cell density-dependent manner. Cytochemical analysis of the stimulation of ALP activity by 1,25(OH)2D3 showed that 1,25(OH)2D3 increased the number of TE85 cells that expressed detectable ALP activity, suggesting that 1,25(OH)2D3 promoted the process …


Cells That Express All Five Proteins Of Vesicular Stomatitis Virus From Cloned Cdnas Support Replication, Assembly, And Budding Of Defective Interfering Particles, Asit K. Pattnaik, Gail W. Wertz Feb 1991

Cells That Express All Five Proteins Of Vesicular Stomatitis Virus From Cloned Cdnas Support Replication, Assembly, And Budding Of Defective Interfering Particles, Asit K. Pattnaik, Gail W. Wertz

School of Veterinary and Biomedical Sciences: Faculty Publications

An alternative approach to structurefunction analysis of vesicular stomatitis virus (VSV) gene products and their interactions with one another during each phase of the viral life cycle is described. We showed previously by using the vaccinia viruslT7 RNA polymerase expression system that when cells expressing the nucleocapsid protein (N), the phosphoprotein (NS), and the large polymerase protein (L) of VSV were superinfected with defective interfering (DI) particles, rapid and efflicient replication and amplification of DI particle RNA occurred. Here, we demonstrate that all five VSV proteins can be expressed simultaneously when cells are cotransfected with plasmids containing the matrix protein …


Thermodynamics Of Charged Oligopeptide Nucleic Acid Interactions, David Mascotti, T. Lohman Jan 1991

Thermodynamics Of Charged Oligopeptide Nucleic Acid Interactions, David Mascotti, T. Lohman

David P. Mascotti

No abstract provided.


Interleukin-1 Or Phorbol Induction Of The Stromelysin Promoter Requires An Element That Cooperates With Ap-1., Karen Sirum-Connolly, Constance E. Brinckerhoff Jan 1991

Interleukin-1 Or Phorbol Induction Of The Stromelysin Promoter Requires An Element That Cooperates With Ap-1., Karen Sirum-Connolly, Constance E. Brinckerhoff

Dartmouth Scholarship

Interieukin-1, a mediator of inflammation, or tumor promoting phorbol esters induce transcription of stromelysin, a metalloproteinase that degrades extracellular matrix molecules and that is overexpressed in diseases such as rheumatoid arthritis. Sequences required for induction of transcription of the human stromelysin promoter are contained on a 46 base pair fragment. This fragment contains a sequence with a high degree of similarity to the binding site for the transcription factor activator protein-1 (AP-1) and indeed, the AP-1 sequence of this fragment is necessary but not sufficient for the maximal response to phorbol 12-myristate 13-acetate (phorbol) or interleukin-1. Maximal induction requires functional …


The Effects Of Chronic Ethanol Exposure Of The Dopaminergic System Of The Rat Brain, Susan Marie Pellegrino Jan 1991

The Effects Of Chronic Ethanol Exposure Of The Dopaminergic System Of The Rat Brain, Susan Marie Pellegrino

Dissertations

No abstract provided.


Ganglioside Metabolism In Embryonic Chick Neurons, Michael Victor Hogan Jan 1991

Ganglioside Metabolism In Embryonic Chick Neurons, Michael Victor Hogan

Dissertations

No abstract provided.


Induction Of Gene Expression In Response To Stress In Pseudomonas Aeruginosa Pao, Audrey L. Warner-Bartnicki Jan 1991

Induction Of Gene Expression In Response To Stress In Pseudomonas Aeruginosa Pao, Audrey L. Warner-Bartnicki

Dissertations

No abstract provided.


Use Of Affinity Chromatography In Developing Acridinium Ester-Labeled Antibodies For An Immunometric Assay Of Parathyrin, David S. Hage, Bob Taylor, Pat Schryver, Pai C. Kao Jan 1991

Use Of Affinity Chromatography In Developing Acridinium Ester-Labeled Antibodies For An Immunometric Assay Of Parathyrin, David S. Hage, Bob Taylor, Pat Schryver, Pai C. Kao

David Hage Publications

In developing an immunometric assay of intact parathyrin (parathyroid hormone, PTH), we found that affinity chromatography is a useful tool in purifying and optimizing the labeling conditions for acridinium ester-labeled antibodies. ... In summary, affinity chromatography was found to be useful in the purification of acridinium ester-labeled antibodies, particularly for removing denatured antibodies from the prepared label and for monitoring the amount of active labeled antibodies produced.


Phenology And Bionomics Of Culicoides (Diptera: Ceratopogonidae) In Glynn County, Georgia, Lisa M. Westberry Jan 1991

Phenology And Bionomics Of Culicoides (Diptera: Ceratopogonidae) In Glynn County, Georgia, Lisa M. Westberry

Legacy ETDs

Seasonal abundance and population densities of Culicoides species from sites in Glynn County, Georgia were surveyed using 15 New Jersey light traps during a 9-month period from April-December 1990. Environmental effects on the abundances were also analyzed. The three primary species present were: Culicoides furens (Poey), C. hollensis Mellander & Brues, and C. melleus (Coguillett). C. furens were collected year round, but predominantly during the summer. C. hollensis had a bimodal abundance (spring and fall) . C. melleus also had a bimodal abundance (late summer and fall).

Larval habitats of the primary species were identified …


Protein Turnover As A Component In The Light/Dark Regulation Of PhosphoEnolPyruvate Carboxylase Protein-Serine Kinase Activity In C4 Plants, Jin-An Jiao, Cristina Echevarría, Jean Vidal, Raymond Chollet Jan 1991

Protein Turnover As A Component In The Light/Dark Regulation Of PhosphoEnolPyruvate Carboxylase Protein-Serine Kinase Activity In C4 Plants, Jin-An Jiao, Cristina Echevarría, Jean Vidal, Raymond Chollet

Department of Biochemistry: Faculty Publications

Maize leaf phosphoenolpyruvate carboxylase [PEPC; orthophosphate:oxaloacetate carboxy-lyase (phosphorylating), EC 4.1.1.311 protein-serine kinase (PEPC-PK) phosphorylates serine-15 of its target enzyme, thus leading to an increase in catalytic activity and a concomitant decrease in malate sensitivity of this cytoplasmic C4 photosynthesis enzyme in the light. We have recently demonstrated that the PEPC-PK activity in maize leaves is slowly, but strikingly, increased in the light and decreased in darkness. In this report, we provide evidence that cycloheximide, an inhibitor of cytoplasmic protein synthesis, when fed to detached leaves of C4 monocots (maize, sorghum) and dicots (Portulaca oleracea) in the …


In Vivo Regulatory Phosphorylation Site In C4-Leaf Phosphoenolpyruvate Carboxylase From Maize And Sorghum, Jin-An Jiao, Jean Vidal, Cristina Echevarría, Raymond Chollet Jan 1991

In Vivo Regulatory Phosphorylation Site In C4-Leaf Phosphoenolpyruvate Carboxylase From Maize And Sorghum, Jin-An Jiao, Jean Vidal, Cristina Echevarría, Raymond Chollet

Department of Biochemistry: Faculty Publications

Reversible seryl-phosphorylation contributes to the light/dark regulation of C4-leaf phosphoenolpyruvate carboxylase (PEPC) activity in vivo. The specific regulatory residue that, upon in vitro phosphorylation by a maize-leaf protein-serine kinase(s), leads to an increase in catalytic activity and a decrease in malatesensitivity of the target enzyme has been recently identified as Ser-15 in 32P-phosphorylated/activated dark-form maize PEPC (J-A Jiao, R Chollet [1990] Arch Biochem Biophys 283: 300-305). In order to ascertain whether this N-terminal seryl residue is, indeed, the in vivo regulatory phosphorylation site, [32P]phosphopeptides were isolated and purified from in vivo 32P-labeled maize and …