The 5.6-Kilodalton Protein in Isolated Chlorosomes of Chloroflexus aurantiacus Strain Ok -70-fl is a Degradation Product

1990 ◽  
Vol 45 (7-8) ◽  
pp. 823-828 ◽  
Author(s):  
Kai Griebenow ◽  
Alfred R. Holzwarth ◽  
Kurt Schaffner
Keyword(s):  
Protease Inhibitors ◽  
Proteolytic Activity ◽  
Degradation Product ◽  
Room Temperature ◽  
Chloroflexus Aurantiacus ◽  
Minor Amount ◽  
Phenylmethylsulfonyl Fluoride ◽  
A Minor

Abstract Chlorosomcs containing BChl a790 have been isolated from Chloroflexus aurantiacus on sucrose density gradients using the detergents Miranol. Deriphat. N.N-dimethyldodecyl- aminc-N-oxidc, and dodecyl-p-D-rnaltoside. All freshly prepared samples cither lack the poly- peptide of approximately 5 kDa. which appears identical with the 5.6-kDa protein previously assigned the role of BChl c-binding [R. G. Feick and R. C. Fuller. Biochemistry 23, 3693- 3700 (1984)]. or they contain only a minor amount thereof. This polypeptide accumulates in the chlorosomcs in vitro at room temperature within 24 h after isolation. The reaction cannot be prevented simply by addition of the protease inhibitors benzamidinc. F.-caproic ac|d. and phenylmethylsulfonyl fluoride. However, upon denaturation, as required lor gel electrophore- sis, of the freshly isolated chlorosome sample the formation of the 5-kDa polypeptide is inhibit- ed. We conclude that this species, viz. 5.6-kDa protein, is a degradation product of another - as yet unidentified - protein present in the chlorosome preparations. Despite the pronounced proteolytic activity which affords the 5-kDa fragment, the native absorption and fluorescence properties of BChl c and BChl a arc essentially not changed in these chlorosome preparations.

CLAY-INORGANIC STUDIES. II. HYDROXY ALUMINUM PHOSPHATE–MONTMORILLONITE COMPLEX

1975 ◽  
Vol 55 (2) ◽  
pp. 225-233 ◽  
Author(s):  
H. KODAMA ◽  
M. D. WEBBER
Keyword(s):  
Relative Humidity ◽  
Room Temperature ◽  
Aluminum Phosphate ◽  
Silicate Layer ◽  
Basal Spacing ◽  
Minor Amount ◽  
Chemical Compositions ◽  
A Minor ◽  
Positively Charged ◽  
Water Contents

Two specimens of hydroxy aluminum phosphate interlayer materials in montmorillonite clay were prepared with 7.20 meq Al and 11.29 meq H3PO4/g clay and with 14.40 meq Al and 22.58 meq H3PO4/g clay, and the resulting complexes studied by chemical and mineralogical methods. Both interlayer materials were slightly positively charged and except for different water contents their chemical compositions were almost identical. They contained Al, PO4 and H2O and a minor amount of Ca and approximated hydrous AlPO4∙nH2O. The mole ratios of Al:Ca:PO4:OH were 1.00:0.08:0.92:0.24 and 1.00:0.05:0.91:0.24, respectively. The interlayer materials appeared to be loosely packed and distributed sparsely in interspaces of the montmorillonite. The degree of packing was greater for the preparation with the larger amount of interlayer material. The materials increased the montmorillonite basal spacing to 23.3 Å under air-dry condition (30–40% relative humidity) but did not affect the lateral dimensions. The basal spacing varied somewhat with relative humidity at room temperature and decreased markedly as water was driven off by heating. Heat treatments between room temperature and 300 C sharply reduced the d001 spacings to 16.7 Å which persisted up to 700 C. It is postulated that the large basal spacings occur because the hydrated interlayer materials have a framework structure with tunnels along the c-axis. This being so, changes in the spacings with different humidities might result from the movement of water molecules among interstitial spaces existing around and between the loosely distributed molecules of interlayer material. The 16.7 Å spacing for the dehydrated phase corresponds to the sum of 7.0 Å, the edge dimension of an orthorhombic anhydrous AlPO4 and 9.7 Å, the silicate layer thickness.

scholarly journals The role of disulphide bonds in human intestinal mucin

1979 ◽  
Vol 181 (3) ◽  
pp. 725-732 ◽  
Author(s):  
Janet F. Forstner ◽  
Inderjit Jabbal ◽  
Rauf Qureshi ◽  
David I. C. Kells ◽  
Gordon G. Forstner
Keyword(s):  
Goblet Cell ◽  
Buoyant Density ◽  
Minor Amount ◽  
Mucin 1 ◽  
Acetylneuraminic Acid ◽  
Disulphide Bonds ◽  
Intestinal Mucin ◽  
Mucin 2 ◽  
A Minor

Goblet-cell mucin (mucin 1) was isolated and purified from human small-intestinal scrapings. After application of mucin 1 to DEAE-Bio-Gel (A) columns, most of the glycoprotein (76–94% of hexoses) was eluted in the first peak (designated mucin 2). Minor amounts of acidic glycoproteins were eluted with 0.2m- and 0.4m-NaCl in later peaks. Analyses of mucin 1 and mucin 2 revealed mucin 2 to be a monodisperse highly glycosylated glycoprotein containing 6.3% by wt. of protein, N-acetylgalactosamine, N-acetylglucosamine, galactose and fucose. Mucin 1 was similar in composition, but was polydisperse and contained more protein (12.3% by wt.) as well as N-acetylneuraminic acid. Analytical CsCl-gradient ultracentrifugation showed both mucin 1 and mucin 2 to have a major component with an average buoyant density of 1.47000g/ml. Mucin 1 also contained a slightly less-dense minor glycoprotein component. After exhaustive reduction and alkylation mucin 1 retained its major component, but partly dissociated into two lighter glycoprotein components. Mucin 2, in contrast, did not change its density distribution after reduction. Band ultracentrifugation in 2H2O-containing iso-osmotic buffers showed that mucin 1 contained a major fast-sedimenting component (so=37±2S), and a minor amount of a slower-sedimenting component. After reduction there was an increased quantity of the latter component, for which an so value of 14.5S was calculated. In contrast, mucin 2 was unaltered by reduction (so=33±2S). These findings indicate that the major component of goblet-cell mucin (mucin 2) does not dissociate after S–S-bond reduction, and thus does not apparently rely for its polymeric structure on the association of subunits through covalent disulphide bonds. However, the effects of reduction on mucin 1 suggest that in the native mucin intramolecular disulphide bonds in the minor glycoproteins may stabilize their structure, permitting secondary non-covalent interactions to develop with the major dense mucin (mucin 2) protein.

scholarly journals Influence of Sodium Dodecyl Sulfonate on the Formation of ZnO Nanorods fromε-Zn(OH)2

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Jing Wang ◽  
Chengxiang Liu ◽  
Lan Xiang
Keyword(s):  
Aspect Ratio ◽  
Molecular Simulation ◽  
Room Temperature ◽  
Zno Nanorods ◽  
Sodium Dodecyl ◽  
Experimental Results ◽  
Minor Amount ◽  
Sodium Dodecyl Sulfonate ◽  
Naoh Solution ◽  
A Minor

The influence of sodium dodecyl sulfonate (SDSN) on the formation of ZnO nanorods fromε-Zn(OH)2was investigated in this paper. Theε-Zn(OH)2precursor was prepared at room temperature using ZnSO4and NaOH as the reactants and then converted to ZnO nanorods after aging at 80°C in NaOH solution containing a minor amount of sodium dodecyl sulfonate (SDSN). The experimental results and the molecular simulation revealed that the influence of SDSN on the formation of ZnO fromε-Zn(OH)2should be attributed to the adsorption of SDSN onε-Zn(OH)2surfaces, which inhibited the dissolution ofε-Zn(OH)2in NaOH solution, leading to the formation of the ZnO nanorods with a diameter of 50–200 nm, a length of 3.0–15.0 μm, and an aspect ratio of 30–100.

scholarly journals Saquinavir Inhibits the Malaria Parasite's Chloroquine Resistance Transporter

2012 ◽  
Vol 56 (5) ◽  
pp. 2283-2289 ◽  
Author(s):  
Rowena E. Martin ◽  
Alice S. Butterworth ◽  
Donald L. Gardiner ◽  
Kiaran Kirk ◽  
James S. McCarthy ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Heterologous Expression ◽  
Protease Inhibitors ◽  
Chloroquine Resistance ◽  
Content Type ◽  
Chloroquine Resistance Transporter ◽  
Resistant Phenotype ◽  
Transgenic Parasites

ABSTRACTThe antiretroviral protease inhibitors (APIs) ritonavir, saquinavir, and lopinavir, used to treat HIV infection, inhibit the growth ofPlasmodium falciparumat clinically relevant concentrations. Moreover, it has been reported that these APIs potentiate the activity of chloroquine (CQ) against this parasitein vitro. The mechanism underlying this effect is not understood, but the degree of chemosensitization varies between the different APIs and, with the exception of ritonavir, appears to be dependent on the parasite exhibiting a CQ-resistant phenotype. Here we report a study of the role of theP. falciparumchloroquine resistance transporter (PfCRT) in the interaction between CQ and APIs, using transgenic parasites expressing different PfCRT alleles and using theXenopus laevisoocyte system for the heterologous expression of PfCRT. Our data demonstrate that saquinavir behaves as a CQ resistance reverser and that this explains, at least in part, its ability to enhance the effects of CQ in CQ-resistantP. falciparumparasites.

Role of proteolysis in copper homoeostasis

2002 ◽  
Vol 30 (4) ◽  
pp. 688-691 ◽  
Author(s):  
M. Solioz
Keyword(s):  
Proteolytic Activity ◽  
Enterococcus Hirae ◽  
Cell Lysates ◽  
Copper Atpases ◽  
Cop Operon

The cop operon of Enterococcus hirae controls cytoplasmic copper levels. It encodes two copper ATPases, a repressor, and the CopZ metallo-chaperone. Transcription of these genes is induced by copper. However, at higher copper concentrations, CopZ is degraded by a copper-activated proteolytic activity. This specific proteolysis of CopZ can also be demonstrated in vitro with E. hirae extracts. Growth of the cells in copper increases the copper-inducible proteolytic activity in extracts. Zymography reveals the presence of a copper-dependent protease in crude cell lysates. Copper-stimulated proteolysis of CopZ appears to play an important role in copper homoeostasis by E. hirae.

scholarly journals RNA binding activates RIG-I by releasing an autorepressed signaling domain

2019 ◽  
Vol 5 (10) ◽  
pp. eaax3641 ◽  
Author(s):  
T. H. Dickey ◽  
B. Song ◽  
A. M. Pyle
Keyword(s):  
Rna Binding ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Fluorescent Labeling ◽  
Minor Role ◽  
Signaling Domain ◽  
A Minor ◽  
Dual Site

The retinoic acid–inducible gene I (RIG-I) innate immune receptor is an important immunotherapeutic target, but we lack approaches for monitoring the physical basis for its activation in vitro. This gap in our understanding has led to confusion about mechanisms of RIG-I activation and difficulty discovering agonists and antagonists. We therefore created a novel fluorescence resonance energy transfer–based method for measuring RIG-I activation in vitro using dual site-specific fluorescent labeling of the protein. This approach enables us to measure the conformational change that releases the signaling domain during the first step of RIG-I activation, making it possible to understand the role of stimulatory ligands. We have found that RNA alone is sufficient to eject the signaling domain, ejection is reversible, and adenosine triphosphate plays but a minor role in this process. These findings help explain RIG-I dysfunction in autoimmune disease, and they inform the design of therapeutics targeting RIG-I.

scholarly journals Proteolytic Activity in the Midgut of the Crimson Speckled Moth Utethesia Pulchella L. (Lepidoptera: Arctiidae)

2012 ◽  
Vol 52 (3) ◽  
pp. 368-373 ◽  
Author(s):  
Maryam Ajamhassani ◽  
Arash Zibaee ◽  
Jalal Sendi ◽  
Hassan Askary ◽  
Nasser Farrar
Keyword(s):  
Pest Management ◽  
Protease Inhibitors ◽  
Proteolytic Activity ◽  
Trypsin Inhibitor ◽  
Serine Proteinases ◽  
Optimal Temperature ◽  
Phenylmethylsulfonyl Fluoride ◽  
Chymotrypsin Inhibitor ◽  
High Proteolytic Activity ◽  
Optimal Ph

Proteolytic Activity in the Midgut of the Crimson Speckled MothUtethesia PulchellaL. (Lepidoptera: Arctiidae)Samples were prepared from the midgut of 4th instar larvae of the crimson speckled mothUtethesia pulchellaL. to find proteolytic activity and properties. Result revealed the presence of high proteolytic activity in the midgut when taking into account specific proteinases including trypsin-like, chymotrypsin-like, elastase and two exopeptidase (aminopeptidase and carboxipeptidase). The optimal pH of general protease was 8 and 7 when using azocasein and hemoglobin as general substrates, respectively. The optimal temperature of the total proteolytic activity in the midgut ofU. pulchellawas 25°C and 30°C when using azocasein and hemoglobin, respectively. Proteolytic activity was inhibited significantly by soybean trypsin inhibitor (SBTI), phenylmethylsulfonyl fluoride (PMSF), trypsin inhibitor (TLCK), chymotrypsin inhibitor (TPCK) and Phenanthroline. These results provide evidences for the presence of serine proteinases as the major proteases in the midgut ofU. pulchella;a key rangeland pest in warm climates. The interaction between digestive proteases and protease inhibitors have potentially important consequences for pest management programs.

scholarly journals SLUG and Truncated TAL1 Reduce Glioblastoma Stem Cell Growth Downstream of Notch1 and Define Distinct Vascular Subpopulations in Glioblastoma Multiforme

Cancers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 5393
Author(s):  
Sophie Guelfi ◽  
Béatrice Orsetti ◽  
Virginie Deleuze ◽  
Valérie Rigau ◽  
Luc Bauchet ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Molecular Mechanisms ◽  
Epithelial To Mesenchymal Transition ◽  
Growth Factor Receptor ◽  
Treatment Resistance ◽  
Mesenchymal Transition ◽  
Glioblastoma Stem Cell ◽  
A Minor

Glioblastomas (GBM) are high-grade brain tumors, containing cells with distinct phenotypes and tumorigenic potentials, notably aggressive and treatment-resistant multipotent glioblastoma stem cells (GSC). The molecular mechanisms controlling GSC plasticity and growth have only partly been elucidated. Contact with endothelial cells and the Notch1 pathway control GSC proliferation and fate. We used three GSC cultures and glioma resections to examine the expression, regulation, and role of two transcription factors, SLUG (SNAI2) and TAL1 (SCL), involved in epithelial to mesenchymal transition (EMT), hematopoiesis, vascular identity, and treatment resistance in various cancers. In vitro, SLUG and a truncated isoform of TAL1 (TAL1-PP22) were strongly upregulated upon Notch1 activation in GSC, together with LMO2, a known cofactor of TAL1, which formed a complex with truncated TAL1. SLUG was also upregulated by TGF-β1 treatment and by co-culture with endothelial cells. In patient samples, the full-length isoform TAL1-PP42 was expressed in all glioma grades. In contrast, SLUG and truncated TAL1 were preferentially overexpressed in GBMs. SLUG and TAL1 are expressed in the tumor microenvironment by perivascular and endothelial cells, respectively, and to a minor extent, by a fraction of epidermal growth factor receptor (EGFR) -amplified GBM cells. Mechanistically, both SLUG and truncated TAL1 reduced GSC growth after their respective overexpression. Collectively, this study provides new evidence for the role of SLUG and TAL1 in regulating GSC plasticity and growth.

Interfacial Reactions of Mo with Al: Ion mixing Versus Thermal Annealing

1988 ◽  
Vol 100 ◽  
Author(s):  
E. Ma ◽  
A. J. Brunner ◽  
T. W. Workman ◽  
C. W. Nieh ◽  
X.-A. Zhao ◽  
...  
Keyword(s):  
Thermal Annealing ◽  
Room Temperature ◽  
Ion Beam ◽  
Dose Dependence ◽  
Interfacial Reactions ◽  
Mixing Efficiency ◽  
Minor Role ◽  
Thermal Spike ◽  
A Minor

ABSTRACTInterfacial reactions induced by ion beam mixing and furnace annealing in Al/Mo bilayers are investigated. The amount of interfacial ion m'xing, 4Dt, follows a linear dose dependence for irradiation temperatures ≤80 C. Below room temperature, the mixing efficiency, defined as d(4Dt)/dø, is temperature independent, and agrees fairly well with the prediction of the phenomenological model based on chemically biased diffusion in thermal spike. We conclude that thermal spike mixing dominates for Xe irradiation of Al/Mo at low temperatures. The mixing efficiency becomes temperature-dependent above room temperature with an apparent activation enthalpy of about 0.17±0.02eV. A layer of 15–20 at.% Mo forms by ion mixing, while oAl12 Mo forms upon thermal annealing in a nonuniform fashion starting at 500°C. Reaction of Mo with large-grained Al substrates shows the same nonuniform characteristics as in evaporated Al/Mo bilayers, implying a minor role of grain boundary effects. Oxygen gettered in the Mo film could be an important factor that influences the interfacial reaction.

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