Effect of membrane perturbing treatments on the membrane-bound peptidases ofStreptococcus cremorisHP

1979 ◽  
Vol 46 (3) ◽  
pp. 473-484 ◽  
Author(s):  
Fred A. Exterkate
Keyword(s):  
Intact Cells ◽  
Irreversible Inhibition ◽  
Alkaline Conditions ◽  
Membrane Bound ◽  
Functional Peptide ◽  
Solvent Molecules ◽  
And Storage ◽  
No Activation ◽  
Proline Iminopeptidase

SummaryThe effects of solubilization, treatment with organic solvents and storage under alkaline conditions on membrane-associated peptidases of intact cells ofStreptococcus cremorisHP were studied. Differences in the response of the peptidase activities towards these membrane perturbing treatments were observed. Pyrrolidonecarboxylylpeptidase (PCP) and an endopeptidase (P50) showed 50% irreversible inhibition at the same concentration of each solvent tested. An amino- and proline iminopeptidase activity and the endopeptidase P37were in this respect much more sensitive to the action of the solvents. Within a homologous series of n-alkanols irreversible inhibition of PCP showed a dependence on the hydrophobicity of the solvent molecules. Only P37activity was increased considerably upon solubilization of the enzyme. Similar levels of activation were found upon treatment of cells with 3% (v/v) n-butanol at 25 °C or storage at 30 °C at an alkaline pH. Optimal activity of P50during n-butanol treatment was at 25 °C using a concentration of 5% (v/v), but no activation was observed upon solubilization. The results are discussed in terms of enzyme–lipid interaction and accessibility of the enzymes in situ. It is concluded that the enzymes apparently occupy different positions within the membrane although they may together constitute a functional peptide-hydrolysing unit.

scholarly journals Cotton fibers bleaching through in situ electrochemical generation of oxidant agents

2021 ◽  
Vol 10 (10) ◽  
pp. e318101018928
Author(s):  
Carolline Schreiber ◽  
Eduardo Zapp ◽  
Cátia Rosana Lange de Aguiar ◽  
Patrícia Bulegon Brondani
Keyword(s):  
Reaction Times ◽  
High Energy ◽  
Cotton Fibers ◽  
Fiber Damage ◽  
Chemical Oxidants ◽  
Alkaline Conditions ◽  
Cotton Bleaching ◽  
And Storage ◽  
High Energy Consumption

Cotton is the world’s leading fiber crop and contains natural coloring impurities which need to be removed by bleaching. The most applied bleaching methodology utilizes chemical oxidants, such as hydrogen peroxide. This method is carried out at high temperatures and under strong alkaline conditions, entailing high-energy consumption, strong alkaline effluents and severe fiber damage. The development of milder and greener bleaching processes, in which the fibers are less damaged, is a goal that has long been pursued. Another approach for cotton bleaching is the use of sodium hypochlorite as an oxidant. Several methods applying hypochlorite are known, but they face problems associated with the transport, storage and handling of unstable and hazardous chemicals. Here we present a mild methodology for in situ electrogeneration of hypochlorite from sodium chloride or potassium chloride, and its application in bleaching of cotton, thus reducing the problems associated with the transport and storage of the oxidizing reagent. Our methodology was able to bleach the cotton fibers with a comparable whiteness degree, when compared to the conventional one, and it is carried out in lower reaction times, at room temperature, with no need of addition of hazardous materials and avoiding the production of residual hypochlorite.

Detection and mapping of interactions between chromatin and the nuclear envelope in drosophila embryos

1995 ◽  
Vol 53 ◽  
pp. 764-765
Author(s):  
W.F. Marshall ◽  
A.F. Dernburg ◽  
B. Harmon ◽  
J.W. Sedat
Keyword(s):  
Nuclear Envelope ◽  
Chromatin Condensation ◽  
Three Dimensional ◽  
Physiological Role ◽  
Nuclear Surface ◽  
Intact Cells ◽  
Molecular Determinants ◽  
Surface Harmonic ◽  
Drosophila Embryos

Interactions between chromatin and nuclear envelope (NE) have been implicated in chromatin condensation, gene regulation, nuclear reassembly, and organization of chromosomes within the nucleus. To further investigate the physiological role played by such interactions, it will be necessary to determine which loci specifically interact with the nuclear envelope. This will not only facilitate identification of the molecular determinants of this interaction, but will also allow manipulation of the pattern of chromatin-NE interactions to probe possible functions. We have developed a microscopic approach to detect and map chromatin-NE interactions inside intact cells.Fluorescence in situ hybridization (FISH) is used to localize specific chromosomal regions within the nucleus of Drosophila embryos and anti-lamin immunofluorescence is used to detect the nuclear envelope. Widefield deconvolution microscopy is then used to obtain a three-dimensional image of the sample (Fig. 1). The nuclear surface is represented by a surface-harmonic expansion (Fig 2). A statistical test for association of the FISH spot with the surface is then performed.

scholarly journals Effects of processing, moisture, and storage length on the fermentation profile, particle size, and ruminal disappearance of reconstituted corn grain

2020 ◽  
Vol 98 (11) ◽  
Author(s):  
Ana L M Gomes ◽  
Antonio V I Bueno ◽  
Fernando A Jacovaci ◽  
Guilherme Donadel ◽  
Luiz F Ferraretto ◽  
...  
Keyword(s):  
Particle Size ◽  
Lactic Acid ◽  
Butyric Acid ◽  
Hammer Mill ◽  
Moisture Concentration ◽  
Fermentation Profile ◽  
And Storage ◽  
Ground Corn ◽  
Corn Grain

Abstract Our objective was to examine the effects of processing, moisture, and anaerobic storage length of reconstituted corn grain (RCG) on the fermentation profile, geometric mean particle size (GMPS), and ruminal dry matter disappearance (DMD). Dry corn kernels were ground (hammer mill, 5-mm screen) or rolled, then rehydrated to 30%, 35%, or 40% moisture, and stored for 0, 14, 30, 60, 90, 120, or 180 d in laboratory silos. Rolled corn had an increased GMPS compared with ground corn (2.24 and 1.13 mm, respectively, at ensiling). However, there was a trend for an interaction between processing and moisture concentration to affect particle size, with GMPS increasing with increased moisture concentration, especially in ground corn. Longer storage periods also slightly increased GMPS. Processing, moisture, and storage length interacted to affect the fermentation pattern (two- or three-way interactions). Overall, pH decreased, whereas lactic acid, acetic acid, ethanol, and NH3-N increased with storage length. RCG with 30% moisture had less lactic acid than corn with 35% and 40% moisture, indicating that fermentation might have been curtailed and also due to the clostridial fermentation that converts lactic acid to butyric acid. Ensiling reconstituted ground corn with 30% of moisture led to greater concentrations of ethanol and butyric acid, resulting in greater DM loss than grain rehydrated to 35% or 40% of moisture. Ammonia-N and in situ ruminal DMD were highest for reconstituted ground corn with 35% or 40% of moisture, mainly after 60 d of storage. Therefore, longer storage periods and greater moisture contents did not offset the negative effect of greater particle size on the in situ ruminal DMD of rolled RCG. Nonetheless, RCG should be ensiled with more than 30% moisture and stored for at least 2 mo to improve the ruminal DMD and reduce the formation of ethanol and butyric acid.

Revealing the structural transformation of rutile RuO2via in situ X-ray absorption spectroscopy during the oxygen evolution reaction

2019 ◽  
Vol 48 (21) ◽  
pp. 7122-7129 ◽  
Author(s):  
Chia-Jui Chang ◽  
You-Chiuan Chu ◽  
Hao-Yu Yan ◽  
Yen-Fa Liao ◽  
Hao Ming Chen
Keyword(s):  
Oxygen Evolution ◽  
Structural Transformation ◽  
Absorption Spectroscopy ◽  
Oxygen Evolution Reaction ◽  
The State ◽  
X Ray ◽  
Alkaline Conditions ◽  
X Ray Absorption ◽  
State Of Art

The state-of-art RuO2 catalyst for the oxygen evolution reaction (OER) is measured by using in situ X-ray absorption spectroscopy (XAS) to elucidate the structural transformation during catalyzing the reaction in acidic and alkaline conditions.

scholarly journals Competition between Metals for Binding to Methanobactin Enables Expression of Soluble Methane Monooxygenase in the Presence of Copper

2014 ◽  
Vol 81 (3) ◽  
pp. 1024-1031 ◽  
Author(s):  
Bhagyalakshmi Kalidass ◽  
Muhammad Farhan Ul-Haque ◽  
Bipin S. Baral ◽  
Alan A. DiSpirito ◽  
Jeremy D. Semrau
Keyword(s):  
Methane Monooxygenase ◽  
High Specificity ◽  
Copper Uptake ◽  
Content Type ◽  
Soluble Methane Monooxygenase ◽  
Sds Page ◽  
Genes Encoding ◽  
Key Factor ◽  
Membrane Bound

ABSTRACTIt is well known that copper is a key factor regulating expression of the two forms of methane monooxygenase found in proteobacterial methanotrophs. Of these forms, the cytoplasmic, or soluble, methane monooxygenase (sMMO) is expressed only at low copper concentrations. The membrane-bound, or particulate, methane monooxygenase (pMMO) is constitutively expressed with respect to copper, and such expression increases with increasing copper. Recent findings have shown that copper uptake is mediated by a modified polypeptide, or chalkophore, termed methanobactin. Although methanobactin has high specificity for copper, it can bind other metals, e.g., gold. Here we show that inMethylosinus trichosporiumOB3b, sMMO is expressed and active in the presence of copper if gold is also simultaneously present. Such expression appears to be due to gold binding to methanobactin produced byM. trichosporiumOB3b, thereby limiting copper uptake. Such expression and activity, however, was significantly reduced if methanobactin preloaded with copper was also added. Further, quantitative reverse transcriptase PCR (RT-qPCR) of transcripts of genes encoding polypeptides of both forms of MMO and SDS-PAGE results indicate that both sMMO and pMMO can be expressed when copper and gold are present, as gold effectively competes with copper for binding to methanobactin. Such findings suggest that under certain geochemical conditions, both forms of MMO may be expressed and activein situ. Finally, these findings also suggest strategies whereby field sites can be manipulated to enhance sMMO expression, i.e., through the addition of a metal that can compete with copper for binding to methanobactin.

scholarly journals Aptamers selected against the unglycosylated EGFRvIII ectodomain and delivered intracellularly reduce membrane-bound EGFRvIII and induce apoptosis

2009 ◽  
Vol 390 (2) ◽  
pp. 137-144 ◽  
Author(s):  
Yingmiao Liu ◽  
Chien-Tsun Kuan ◽  
Jing Mi ◽  
Xiuwu Zhang ◽  
Bryan M. Clary ◽  
...  
Keyword(s):  
Growth Factor Receptor ◽  
Rna Aptamers ◽  
Normal Brain ◽  
Post Translational Modification ◽  
Expression And Purification ◽  
Post Translational Modifications ◽  
Protein Expression And Purification ◽  
Epidermal Growth ◽  
Membrane Bound

Abstract Epidermal growth factor receptor variant III (EGFRvIII) is a glycoprotein uniquely expressed in glioblastoma, but not in normal brain tissues. To develop targeted therapies for brain tumors, we selected RNA aptamers against the histidine-tagged EGFRvIII ectodomain, using an Escherichia coli system for protein expression and purification. Representative aptamer E21 has a dissociation constant (Kd) of 33×10-9 m, and exhibits high affinity and specificity for EGFRvIII in ELISA and surface plasmon resonance assays. However, selected aptamers cannot bind the same protein expressed from eukaryotic cells because glycosylation, a post-translational modification present only in eukaryotic systems, significantly alters the structure of the target protein. By transfecting EGFRvIII aptamers into cells, we find that membrane-bound, glycosylated EGFRvIII is reduced and the percentage of cells undergoing apoptosis is increased. We postulate that transfected aptamers can interact with newly synthesized EGFRvIII, disrupt proper glycosylation, and reduce the amount of mature EGFRvIII reaching the cell surface. Our work establishes the feasibility of disrupting protein post-translational modifications in situ with aptamers. This finding is useful for elucidating the function of proteins of interest with various modifications, as well as dissecting signal transduction pathways.

scholarly journals INTEGRINS MEDIATE PLACENTAL EXTRACELLULAR VESICLE TRAFFICKING TO LUNG AND LIVER IN VIVO

2020 ◽  
Author(s):  
Sean L. Nguyen ◽  
Soo Hyun Ahn ◽  
Jacob W. Greenberg ◽  
Benjamin W. Collaer ◽  
Dalen W. Agnew ◽  
...  
Keyword(s):  
Immune Cells ◽  
Extracellular Vesicle ◽  
Dependent Manner ◽  
Cellular Phenotype ◽  
Reporter Mouse ◽  
Membrane Bound ◽  
First Time

ABSTRACTMembrane-bound extracellular vesicles (EVs) mediate intercellular communication in all organisms, and those produced by placental mammals have become increasingly recognized as significant mediators of fetal-maternal communication. Here, we aimed to identify maternal cells targeted by placental EVs and elucidate the mechanisms by which they traffic to these cells. Exogenously administered pregnancy-associated EVs traffic specifically to the lung; further, placental EVs associate with lung interstitial macrophages and liver Kupffer cells in an integrin-dependent manner. Localization of EV to maternal lungs was confirmed in unmanipulated pregnancy using a transgenic reporter mouse model, which also provided in situ and in vitro evidence that fetally-derived EVs, rarely, may cause genetic alteration of maternal cells. These results provide for the first time direct in vivo evidence for targeting of placental EVs to maternal immune cells, and further, evidence that EVs can alter cellular phenotype.

scholarly journals IN SITU DETERMINATIONS OF pH IN SOME LAKES

1971 ◽  
Vol 2 (3) ◽  
pp. 133-145 ◽  
Author(s):  
OLAV GRÖTERUD
Keyword(s):  
Water Samples ◽  
And Storage ◽  
In Situ Technique

pH has been determined in some lakes by using an in situ technique. pH has also been measured in the usual way in the field and in the laboratory. These measurements, together with the determinations in situ, made it possible to get information about changes of pH in the water samples during sampling, measuring, and storage. The microstratification of pH has also been investigated by means of in situ determinations.

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