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Full-Text Articles in Life Sciences

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.


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 …


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 …


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 …


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 …


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 …


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.


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 …


Purification And Characterization Of Soybean Root Nodule Ferric Leghemoglobin Reductase, Lin Ji, Stephen Wood, Manuel Becana, Robert V. Klucas Jan 1991

Purification And Characterization Of Soybean Root Nodule Ferric Leghemoglobin Reductase, Lin Ji, Stephen Wood, Manuel Becana, Robert V. Klucas

Department of Biochemistry: Faculty Publications

A ferric leghemoglobin reductase from the cytosol of soybean (Glyclne max) root nodules was purified to homogeneity and partlafly characterized. The enzyme is a flavoprotein with flavin adenine dinuclotide as the prosthetic group and consists of two identical subunits, each having a molecular mass of 54 kilodaltons. The pure enzyme shows a high activity for ferric leghemoglobin reduction with NADH as the reductant in the absence of any exogenous mediators. The enzyme also exhibits NADH-dependent 2,6-dichloroindophenol reductase activity. A sequence of the first 50 N-terminal amino acids of the purified protein was obtained. Comparisons with known protein sequences …


Posttranslational Regulation Of Phosphoenolpyruvate Carboxylase In C4 And Crassulacean Acid Metabolism Plants, Jin-An Jiao, Raymond Chollet Jan 1991

Posttranslational Regulation Of Phosphoenolpyruvate Carboxylase In C4 And Crassulacean Acid Metabolism Plants, Jin-An Jiao, Raymond Chollet

Department of Biochemistry: Faculty Publications

Control of C4 photosynthesis and Crassulacean acid metabolism (CAM) is, in part, mediated by the diel regulation of phosphoenolpyruvate carboxylase (PEPC) activity. The nature of this regulation of PEPC in the leaf cell cytoplasm of C4 and CAM plants is both metabolite-related and posttranslational. Specifically, the regulatory properties of the enzyme vary in accord with the physiological activity of C4 photosynthesis and CAM: PEPC is less sensitive to feedback inhibition by L-malate under light (C4 plants) or at night (CAM plants) than in darkness (C4) or during the day (CAM). While the view that …


Improved Syntheses Of Some Monochloro- And Monobromo-8-Quinolinols / Herman Gershon And Donald D. Clarke Department Of Chemistry, Fordham University, Bronx, Ny 10458, Usa, Herman Gershon, Donald Dudley Clarke Phd Jan 1991

Improved Syntheses Of Some Monochloro- And Monobromo-8-Quinolinols / Herman Gershon And Donald D. Clarke Department Of Chemistry, Fordham University, Bronx, Ny 10458, Usa, Herman Gershon, Donald Dudley Clarke Phd

Chemistry Faculty Publications

Procedures were developed for the preparation of the 2-, 3-, 4-, and 6-monosubstituted chloro and bromo 8-quinolinols which afforded greater yields and/or reduced the number of steps in the preparation. 100 MHz 1H-NMR spectra for the 12 possible monochloro and mono bromo analogues are given


Monoclonal Antibodies To The Fusion Protein Of Bovine Respiratory Syncytial Virus, Kent M. Mulkey, Gary A. Anderson Jan 1991

Monoclonal Antibodies To The Fusion Protein Of Bovine Respiratory Syncytial Virus, Kent M. Mulkey, Gary A. Anderson

School of Veterinary and Biomedical Sciences: Faculty Publications

Five monoclonal antibodies specific for bovine respiratory syncytial virus were characterized by Western immunoblotting, radioimmunoprecipitation, and epitope mapping assays. The monoclonal antibodies were found to be specific for the fusion protein, and there were at least two antigen binding sites, one of which was neutralizing.


Fluoroacetate And Fluorocitrate: Mechanism Of Action / Donald D. Clarke, Donald Dudley Clarke Phd Jan 1991

Fluoroacetate And Fluorocitrate: Mechanism Of Action / Donald D. Clarke, Donald Dudley Clarke Phd

Chemistry Faculty Publications

The concept of lethal synthesis as suggested by Peters is reviewed in the light of the more recent work in this area. It is suggested that fluorocitrate is a "suicide" substrate for aconitase rather than a competitive inhibitor as originally suggested. The use of these substances to study glialneuronal relationships is considered


Evidence Of Steric Factors In The Fungitoxic Mechanism Of 8-Quinolinol And Its 5- And 7-Halogenated Analogues / Herman Gershon, Donald D. Clarke, And Muriel Gershon, Herman Gershon, Donald Dudley Clarke Phd, Muriel Gershon Jan 1991

Evidence Of Steric Factors In The Fungitoxic Mechanism Of 8-Quinolinol And Its 5- And 7-Halogenated Analogues / Herman Gershon, Donald D. Clarke, And Muriel Gershon, Herman Gershon, Donald Dudley Clarke Phd, Muriel Gershon

Chemistry Faculty Publications

Antifungal studies were made of mixtures of minimal inhibitory concentrations (MICs) of 8-quinolinol and its 5- and 7-halo analogues against six fungi: Aspergillus niger, A. oryzae, Trichoderma viride, Myrothecium verrucaria, Mucor cirinelloides, and Trichophyton mentagrophytes. Mixtures of 8-quinolinol with 5- or 7-fluoro-8-quinolinol and of 5- and 7-fluoro-8-quinolinol showed additive activity, and their respective toxicities were reversed by L-cysteine. These results suggested a common mechanism of activity for the three toxicants. Potentiation of the fungitoxicity of mixtures of 8-quinolinol and its 5- and 7-chloro, bromo, and iodo analogues, as well as mixtures of 5- and 7-chloro, 5- and 7-bromo, and 5- …


Nicotinate, Nicotinamide, And The Reactivity Of Leghemoglobin In Soybean Root Nodules, Robert V. Klucas, Cyril A. Appleby Jan 1991

Nicotinate, Nicotinamide, And The Reactivity Of Leghemoglobin In Soybean Root Nodules, Robert V. Klucas, Cyril A. Appleby

Department of Biochemistry: Faculty Publications

Nicotinate has been postulated to interfere with the binding of O2 to ferrous leghemoglobin in soybean (Glycine max) root nodules. For such a function, the levels of nicotinate in nodules must be sufficiently high to bind a significant amount of leghemoglobin. We have measured levels of nicotinate, nicotinamide, and leghemoglobin in soybean nodules from plants 34 to 73 days after planting in a glasshouse. On a per gram nodule fresh weight basis, levels between 10.4 and 21 nanomoles for nicotinate, 19.2 and 37.8 nanomoles for nicotinamide, and 170 to 280 nanomoles for leghemoglobin were measured. Even if …


Detection Of Mercuric Ions In Water By Elisa With A Mercury- Specific Antibody, Dwane E. Wylie, Larry D. Carlson, Randy Carlson, Fred W. Wagner, Sheldon M. Schuster Jan 1991

Detection Of Mercuric Ions In Water By Elisa With A Mercury- Specific Antibody, Dwane E. Wylie, Larry D. Carlson, Randy Carlson, Fred W. Wagner, Sheldon M. Schuster

Department of Biochemistry: Faculty Publications

An immunoassay that detects mercuric ions in water at concentrations of 0.5 ppb and above is described. The assay utilizes a monoclonal antibody that binds specifically to mercuric ions immobilized in wells of microtiter plates. Within the range of 0.5-10 ppb mercury, the absorbance in the enzyme-linked immunosorbent assay (ELISA) is linear to the log of the mercuric ion concentration. The quantitation of mercury by ELISA correlates closely with results from cold-vapor atomic absorption. Other divalent metal cations do not interfere with the assay, although there is interference in the presence of 1 mM chloride ions. The optimum pH for …


Photosynthetic Electron Transport In Genetically Altered Photosystem Ii Reaction Centers Of Chloroplasts, Robin A. Roffey, John H. Golebeck, C. Russ Hille, Richard T. Sayre Jan 1991

Photosynthetic Electron Transport In Genetically Altered Photosystem Ii Reaction Centers Of Chloroplasts, Robin A. Roffey, John H. Golebeck, C. Russ Hille, Richard T. Sayre

Department of Biochemistry: Faculty Publications

Using a cotransformation system to identify chloroplast transformants in Chlamydomonas reinhardtii, we converted histidine-195 of the photosystem H reaction center D1 protein to a tyrosine residue. The mutants were characterized by a reduced quantum efficiency for photosynthetic oxygen evolution, which varied in a pH-dependent manner, a reduced capacity to oxidize artificial donors to photosystem II, and P680+) reduction kinetics (microsecond) that were essentially similar to wild type. In addition, a dark-stable radical was detected by ESR in mutant photosystem II particles but not in wild-type particles. This radical was similar in g value and lineshape to chlorophyll …


Cell Surface-Binding Sites For Progesterone Mediate Calcium Uptake In Human Sperm, Peter F. Blackmore, Joseph Neulan, Frank Lattanzio, Stephen J. Beebe Jan 1991

Cell Surface-Binding Sites For Progesterone Mediate Calcium Uptake In Human Sperm, Peter F. Blackmore, Joseph Neulan, Frank Lattanzio, Stephen J. Beebe

Bioelectrics Publications

Recent studies (e.g. Blackmore, P. F., Beebe, S. J., Danforth, D. R., and Alexander, N.) (1990) J. Biol. Chem. 265, 1376-1380) have shown that in human sperm, progesterone produces a rapid increase in intracellular free calcium ([Ca2+]i) and an induction of the acrosome reaction (e.g. Osman, R. A., Andria, M. L., Jones, A. D., and Meizel, S. (1989) Biochem. Biophys. Res. Commun. 160, 828-833). In this study, the location of progesterone receptors on the cell surface of human sperm was identified using progesterone immobilized on bovine serum albumin (BSA) (progesterone 3-(O-carboxymethyl)oxime:BSA) as well as progesterone and its 3-O-carboxymethyloxime derivative. Using …