scholarly journals Regular structures in unit membranes. II. Morphological and biochemical characterization of two water-soluble membrane proteins isolated from the suckling rat ileum.

1976 ◽  
Vol 70 (1) ◽  
pp. 97-111 ◽  
Author(s):  
E R Jakoi ◽  
G Zampighi ◽  
J D Robertson
Keyword(s):  
High Speed ◽  
Plasma Membranes ◽  
Biochemical Characterization ◽  
Membrane Surface ◽  
Gel Filtration ◽  
Water Soluble ◽  
Regular Structures ◽  
Membrane Surfaces ◽  
Negative Stain ◽  
Ordered Array

Specialized plasma membranes from the endocytic complex of ileal epithelial cells of suckling rats were isolated by differential flotation. Thin-section and negative-stain electron microscopy showed the luminal surfaces of these membranes to be covered by an ordered array of particles 14.5-nm separations in long rows. This particulate coating was released from the membrane surfaces by 10 mM CaCl2 and recovered free of membranes after dialysis against 0.5 mM EGTA and high-speed centrifugation. Two proteins were resolved by gel filtration to be in supernate: n-acetyl-beta-glucosaminidase and a filamentous protein which attaches n-acetylglucosaminidase to the membrane surface thereby providing bidirectionality to the array of enzyme. We believe that the filamentous protein has not been previously described. Therefore we have called it ligatin from the latin ligare, which translates "to bind together". Furthermore, we suggest that the membranes of the endocytic complex contain sites for the extracellular digestion of carbohydrate moieties in the maternal milk.

scholarly journals Binding and structural characteristics of a soluble lactogen-binding protein from rabbit mammary-gland cytosol

1986 ◽  
Vol 237 (3) ◽  
pp. 813-820 ◽  
Author(s):  
S I Ymer ◽  
A C Herington
Keyword(s):  
Mammary Gland ◽  
High Speed ◽  
Plasma Membranes ◽  
Specific Binding ◽  
Binding Protein ◽  
Structural Characteristics ◽  
Polyacrylamide Gel Electrophoresis ◽  
Gel Filtration ◽  
Scatchard Analysis ◽  
Specific Binding Protein

Specific receptors for prolactin (PRL) are known to be present on plasma membranes and intracellular membranes of mammary gland. We now report, however, the detection and characterization of a soluble lactogen-specific binding protein in high-speed (200,000 g) cytosolic preparations from pregnant- and non-pregnant-rabbit mammary gland. The binding protein was not detectable by poly(ethylene glycol) precipitation; instead, bound and free 125I-labelled human growth hormone (hGH; a potent lactogen) was separated using a mini-gel filtration technique. Specific binding of 125I-hGH reached an apparent equilibrium between 10 and 14 h at 21-23 degrees C. It was dependent on mammary-gland protein concentration and, partially, on Ca2+ or Mg2+ concentrations. Scatchard analysis revealed steep curvilinear plots, the high-affinity component having a KA of approximately 3 × 10(10) M-1. Gel filtration on calibrated Ultrogel AcA34 columns of 125I-hGH-cytosol complexes or of cytosol alone, followed by measurement of 125I-hGH binding in each eluted fraction, indicated that the binding protein had an Mr of 33,000-43,000. A specific binding protein of the same size was observed when 125I-ovine or -human PRL, but not 125I-bovine GH, was used as ligand. The apparent lactogenic specificity was confirmed by a lack of cross-reactivity of the binding protein with an anti-[GH receptor (rabbit liver)] monoclonal antibody. Polyacrylamide-gel electrophoresis of 125I-hGH covalently cross-linked to cytosol with disuccinimidyl suberate revealed binding proteins of Mr 35,000 (non-reduced) and 37,000 (reduced), results comparable with those obtained by gel filtration and indicating an absence of inter-subunit disulphide bonds. These studies have shown the presence of an apparently naturally soluble lactogen-binding protein in the cytosolic fraction of rabbit mammary gland. The relationship between this binding protein and the membrane PRL receptor is not yet known.

Saskatchewan Highways and Transportation Reduced Tire Pressure Initiative

1997 ◽  
Vol 1589 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Thomas L. Davies ◽  
Tami F. Wall ◽  
Allan Carpentier
Keyword(s):  
High Speed ◽  
Membrane Surface ◽  
Vehicle Stability ◽  
Road Maintenance ◽  
Long Term Effects ◽  
Tire Pressure ◽  
Reduced Pressure ◽  
Maintenance Costs ◽  
Short And Long Term

After examination of the research carried out by other agencies, Saskatchewan Highways and Transportation (SHT) embarked on an initiative to adapt low tire pressure technologies to the province's needs and environment. The focus of the initiative was to explore several technical questions from SHT's perspective: (a) Can low tire pressures be used to increase truck weights from secondary to primary without increasing road maintenance costs on thin membrane surface roads? (b) What are the short- and long-term effects of tire heating under high-speed/high-deflection constant reduced pressure (CRP) operations in a Saskatchewan environment? (c) What effects do lower tire pressures have on vehicle stability at highway speeds? To date, significant opportunities have been noted on local hauls (less than 30 min loaded at highway speeds) for CRP operation and long primary highway hauls that begin or end in relatively short secondary highway sections that limit vehicle weight allowed for the whole trip for central tire inflation technology. The background and environment for the initiative and the investigations and demonstrations envisioned and undertaken are briefly outlined.

Optimization of Solid Lipid Nanoparticles of Ezetimibe in Combination with Simvastatin Using Quality by Design (QbD)

2020 ◽  
Vol 10 (4) ◽  
pp. 404-418
Author(s):  
Kruti Borderwala ◽  
Ganesh Swain ◽  
Namrata Mange ◽  
Jaimini Gandhi ◽  
Manisha Lalan ◽  
...  
Keyword(s):  
Particle Size ◽  
Solid Lipid Nanoparticles ◽  
High Speed ◽  
Entrapment Efficiency ◽  
Lipid Nanoparticles ◽  
Water Soluble ◽  
Lipid Matrix ◽  
Solid Lipid ◽  
32 Factorial Design ◽  
Full Factorial Experimental Design

Background: The objective of this study was to develop solid lipid nanoparticles (SLNs) of poorly water soluble anti-hyperlipidemic drugs-Ezetimibe in combination with Simvastatin. Methods: This study describes a 32 full factorial experimental design to optimize the formulation of drug loaded lipid nanoparticles (SLN) by the high speed homogenization technique. The independent variables amount of lipid (GMS) and amount of surfactant (Poloxamer 188) were studied at three levels and arranged in a 32 factorial design to study the influence on the response variables- particle size, % entrapment efficiency (%EE) and cumulative drug release (% CDR) at 24 h. Results: The particle size, % EE and % CDR at 24 h for the 9 batches (B1 to B9) showed a wide variation of 104.6-496.6 nm, 47.80-82.05% (Simvastatin); 48.60-84.23% (Ezetimibe) and 54.64-92.27% (Simvastatin); 43.8-97.1% (Ezetimibe), respectively. The responses of the design were analysed using Design Expert 10.0.2. (Stat-Ease, Inc, USA), and the analytical tools of software were used to draw response surface plots. From the statistical analysis of data, polynomial equations were generated. Optimized formulation showed particle size of 169.5 nm, % EE of 75.43% (Simvastatin); 79.10% (Ezetimibe) and 74.13% (Simvastatin); 77.11% (Ezetimibe) %CDR after 24 h. Thermal analysis of prepared solid lipid nanoparticles gave indication of solubilisation of drugs within lipid matrix. Conclusion: Fourier Transformation Infrared Spectroscopy (FTIR) showed the absence of new bands for loaded solid lipid nanoparticles indicating no interaction between drugs and lipid matrix and being only dissolved in it. Electron microscope of transmission techniques indicated sphere form of prepared solid lipid nanoparticles with smooth surface with size approximately around 100 nm.

scholarly journals Purification and characterization of fat body lipase from the greater wax moth, Galleria mellonella (Lepidoptera: Pyralidae)

2019 ◽  
Vol 81 (1) ◽  
Author(s):  
Rahma R. Z. Mahdy ◽  
Shaimaa A. Mo’men ◽  
Marah M. Abd El-Bar ◽  
Emad M. S. Barakat
Keyword(s):  
Metal Ions ◽  
Kinetic Parameters ◽  
Biochemical Characterization ◽  
Galleria Mellonella ◽  
Fat Body ◽  
Specific Activity ◽  
Larval Instar ◽  
Gel Filtration ◽  
Molecular Weights

Abstract Background Insect lipid mobilization and transport are currently under research, especially lipases and lipophorin because of their roles in the production of energy and lipid transport at a flying activity. The present study has been conducted to purify intracellular fat body lipase for the first time, from the last larval instar of Galleria mellonella. Results Purification methods by combination of ammonium sulfate [(NH4)2SO4] precipitation and gel filtration using Sephadex G-100 demonstrated that the amount of protein and the specific activity of fat body lipase were 0.008633 ± 0.000551 mg/ml and 1.5754 ± 0.1042 μmol/min/mg protein, respectively, with a 98.9 fold purity and recovery of 50.81%. Hence, the sephadex G-100 step was more effective in the purification process. SDS-PAGE and zymogram revealed that fat body lipase showed two monomers with molecular weights of 178.8 and 62.6 kDa. Furthermore, biochemical characterization of fat body lipase was carried out through testing its activities against several factors, such as different temperatures, pH ranges, metal ions, and inhibitors ending by determination of their kinetic parameters with the use of p-nitrophenyl butyrate (PNPB) as a substrate. The highest activities of enzyme were determined at the temperature ranges of 35–37 °C and 37–40 °C and pH ranges of 7–9 and 7–10. The partially purified enzyme showed significant stimulation by Ca2+, K+, and Na+ metal ions indicating that fat body lipase is metalloproteinase. Lipase activity was strongly inhibited by some inhibitors; phenylmethylsulfonyl fluoride (PMSF), ethylene-diaminetetractic acid (EDTA), and ethylene glycoltetraacetic acid (EGTA) providing evidence of the presence of serine residue and activation of enzymes by metal ions. Kinetic parameters were 0.316 Umg− 1 Vmax and 301.95 mM Km. Conclusion Considering the purification of fat body lipase from larvae and the usage of some inhibitors especially ion chelating agents, it is suggested to develop a successful control of Galleria mellonella in near future by using lipase inhibitors.

Thermotropic lipid and protein transitions in Chinese hamster lung cell membranes: relationship to hyperthermic cell killing

1983 ◽  
Vol 61 (6) ◽  
pp. 421-427 ◽  
Author(s):  
James R. Lepock ◽  
Kwan-Hon Cheng ◽  
Hisham Al-Qysi ◽  
Jack Kruuv
Keyword(s):  
Mammalian Cells ◽  
Plasma Membranes ◽  
Chinese Hamster ◽  
Cell Killing ◽  
Water Soluble ◽  
Growth Data ◽  
Protein Fluorescence ◽  
Polar Groups ◽  
Spin Resonance ◽  
Intrinsic Protein Fluorescence

Exposure of mammalian cells to hyperthermic temperatures (ca. 41–45 °C) appears to act as a direct or triggering effect to produce some later response such as cell death, thermotolerance, or heat-shock protein synthesis. The high activation energy of cell killing indicates that the direct effect of hyperthermia might be a thermotropic transition in some cellular component, for this particular response. Both hyperthermic survival and growth data imply that the temperature for the onset of hyperthermic cell killing is 40–41.5 °C for Chinese hamster lung V79 cells. Studies using the electron spin resonance label 2,2-dimethyl-5-dodecyl-5-methyloxazolidine-N-oxide and the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene show the existence of lipid transitions at approximately 7–8 and 23–36 °C (or a broad transition between these temperatures) in mitochondria and whole cell homogenates, that correlate well with changes in growth and hypothermic killing. No lipid transition was detected near 40–41.5 °C that could correlate with hyperthermic killing in either mitochondrial or plasma membranes, but measurements of intrinsic protein fluorescence and protein fluorophore to trans-paranaric acid energy transfer demonstrate the existence of an irreversible transition in protein structure or arrangement above ca. 40 °C in both mitochondrial and plasma membranes. This transition is due to protein rearrangement and (or) unfolding such that there is increased exposure of protein tryptophan and tyrosine residues to polar groups and to paranaric acid. The strength of the transition implies that a significant fraction of total membrane protein is involved in this transition, which may be analogous to the heat-induced denaturation of water-soluble proteins. This alteration in membrane structure above ca. 40 °C could cause many of the observed changes in plasma membrane and mitochondrial function, which may further be involved in cellular responses to hyperthermia.

The biological activity of glucagon–phospholipid complexes

1983 ◽  
Vol 61 (7) ◽  
pp. 688-691 ◽  
Author(s):  
J. J. Liepnieks ◽  
P. Stoskopf ◽  
E. A. Carrey ◽  
C. Prosser ◽  
R. M. Epand
Keyword(s):  
Biological Activity ◽  
Adenylate Cyclase ◽  
Plasma Membranes ◽  
Bovine Brain ◽  
Water Soluble ◽  
Dipalmitoyl Phosphatidylcholine ◽  
Dimyristoyl Phosphatidylcholine ◽  
Lipoprotein Complex ◽  
Stimulation Of

Glucagon can form water-soluble complexes with phospholipids. The incorporation of glucagon into these lipoprotein particles reduces the biological activity of the hormone. The effect is observed only at temperatures below the phase transition temperature of the phospholipid and results in a decreased stimulation of the adenylate cyclase of rat liver plasma membranes by the lipoprotein complex as compared with the hormone in free solution. Two- to five-fold higher concentrations of glucagon are required for half-maximal stimulation of adenylate cyclase when the hormone is complexed with dimyristoyl phosphatidylcholine, dipalmitoyl phosphatidylcholine, or bovine brain sphingomyelin. A possible role of lipoprotein-associated hormones in the development of insulin resistance is discussed.

scholarly journals Characterization of the binding of plasminogen activators to plasma membranes from human liver

1992 ◽  
Vol 287 (3) ◽  
pp. 911-915 ◽  
Author(s):  
G Nguyen ◽  
S J Self ◽  
C Camani ◽  
E K O Kruithof
Keyword(s):  
Human Liver ◽  
Plasma Membranes ◽  
Gel Filtration ◽  
Mannose Receptor ◽  
Hepatoma Cells ◽  
Tissue Type ◽  
High Affinity ◽  
Liver Membranes ◽  
Membrane Bound ◽  
Pai 1

The binding of tissue-type plasminogen activator (t-PA) to membranes prepared from human liver was investigated, and a specific, saturable, high-affinity binding site (Kd = 3.4 nM) was identified. The binding of t-PA to liver membranes was not affected by an excess of D-mannose or D-galactose, or by active urokinase (u-PA), whereas binding of t-PA to membranes prepared from human HepG2 hepatoma cells was inhibited by u-PA. HepG2-membrane-bound t-PA was fully complexed to PA inhibitor 1 (PAI-1), whereas liver-membrane-bound t-PA was not complexed. Gel filtration on Sephacryl S300 of membrane proteins solubilized in deoxycholate revealed that high-affinity t-PA binding activity elutes at an apparent molecular mass of 40 kDa. Monoclonal antibodies specific for the growth factor and the kringle 2 domains inhibited the binding of t-PA to liver membranes and the catabolism of t-PA by rat hepatoma cells. Human liver membranes also bound u-PA; binding was inhibited by pro-u-PA, the N-terminal fragment of u-PA, but not by the 33 kDa form of u-PA or by t-PA. Our results show that human liver membranes contain a specific 40 kDa binding protein for t-PA that is different from the PAI-1-dependent receptor described on HepG2 cells and the mannose receptor isolated from human liver.

scholarly journals Intermediate filaments in non-neuronal cells of invertebrates: isolation and biochemical characterization of intermediate filaments from the esophageal epithelium of the mollusc Helix pomatia.

1985 ◽  
Vol 101 (2) ◽  
pp. 427-440 ◽  
Author(s):  
E Bartnik ◽  
M Osborn ◽  
K Weber
Keyword(s):  
Positive Reaction ◽  
Intermediate Filaments ◽  
Biochemical Characterization ◽  
Helix Pomatia ◽  
Molar Ratio ◽  
Negative Stain ◽  
Epithelial Morphology ◽  
Lower Chordate

To screen invertebrate tissues for the possible expression of intermediate filaments (IFs), immunofluorescence microscopy with the monoclonal antibody anti-IFA known to detect all mammalian IF proteins was used (Pruss, R. M., R. Mirsky, M. C. Raff, R. Thorpe, A. J. Dowding, and B. H. Anderton. 1981. Cell, 27:419-428). In a limited survey, the lower chordate Branchiostoma as well as the invertebrates Arenicola, Lumbricus, Ascaris, and Helix pomatia revealed a positive reaction primarily on epithelia and on nerves, whereas certain other invertebrates appeared negative. To assess the nature of the positive reaction, Helix pomatia was used since a variety of epithelia was strongly stained by anti-IFA. Fixation-extraction procedures were developed that preserve in electron micrographs of esophagus impressive arrays of IFs as tonofilament bundles. Fractionation procedures performed on single cell preparations document large meshworks of long and curvilinear IF by negative stain. These structures can be purified. One- and two-dimensional gels show three components, all of which are recognized by anti-IFA in immunoblotting: 66 kD/pl 6.35, 53 kD/pl 6.05, and 52 kD/pl 5.95. The molar ratio between the larger and more basic polypeptide and the sum of the two more acidic forms is close to 1. After solubilization in 8.5 M urea, in vitro filament reconstitution is induced when urea is removed by dialysis against 2-50 mM Tris buffer at pH 7.8. The reconstituted filaments contain all three polypeptides. The results establish firmly the existence of invertebrate IFs outside neurones and demonstrate that the esophagus of Helix pomatia displays IFs which in line with the epithelial morphology of the tissue could be related to keratin IF of vertebrates.

scholarly journals Stimulation of 5-lipoxygenase activity under conditions which promote lipid peroxidation

1989 ◽  
Vol 263 (2) ◽  
pp. 565-572 ◽  
Author(s):  
D Riendeau ◽  
D Denis ◽  
L Y Choo ◽  
D J Nathaniel
Keyword(s):  
Lipid Peroxidation ◽  
High Speed ◽  
Chemical Reduction ◽  
Gel Filtration ◽  
Maximal Activity ◽  
Lipoxygenase Activity ◽  
Supernatant Fraction ◽  
Acid Oxidation ◽  
Thiol Compounds ◽  
Stimulation Of

The characteristics of hydroperoxide activation of 5-lipoxygenase were examined in the high speed supernatant fraction prepared from rat polymorphonuclear leukocytes. Stimulation of 5-lipoxygenase activity by the 5-hydroperoxyeicosatetraenoic acid (5-HPETE) reaction product was strongly dependent on the presence of thiol compounds. Various reducing agents such as mercaptoethanol and glutathione (0.5-2 mM) inhibited the reaction and increased the concentrations of 5-HPETE (1-10 microM) necessary to achieve maximal arachidonic acid oxidation. The requirement for 5-HPETE was not specific and could be replaced by H2O2 (10 microM) but not by the 5-hydroxyeicosatetraenoic acid (5-HETE) analogue. Furthermore, gel filtration chromatography of the soluble extract from leukocytes resolved different fractions which can increase the hydroperoxide dependence or fully replace the stimulation by 5-HPETE. Maximal activity of the 5-HPETE-stimulated reaction required Ca2+ ions (0.2-1 mM) and ATP with the elimination of the HPETE requirement at high ATP concentrations (2-4 mM). In addition, NADPH (1-2 mM), FAD (1 mM), Fe2+ ions (20-100 microM) and chelated Fe3+ (0.1 mM-EDTA/0.1 mM-FeCl3) all markedly increased product formation by 5-lipoxygenase whereas NADH (1 mM) was inhibitory and Fe3+ (20-100 microM) alone had no effect on the reaction. The stimulation by Fe2+ ions and NADPH was also observed under various conditions which increase the hydroperoxide dependence such as pretreatment of the enzyme preparation with glutathione peroxidase or chemical reduction with 0.015% NaBH4. These results provide evidence for an hydroperoxide activation of 5-lipoxygenase which is not product-specific and is modulated by thiol levels and several soluble components of the leukocytes. They also indicate that stimulation of 5-lipoxygenase activity can contribute to increase lipid peroxidation in iron and nucleotide-promoted reactions.

scholarly journals Purification and characterization of a major glycoprotein in rat hepatoma plasma membranes. One of the membrane proteins released by phosphatidylinositol-specific phospholipase C

1987 ◽  
Vol 241 (1) ◽  
pp. 63-70 ◽  
Author(s):  
Y Ikehara ◽  
Y Hayashi ◽  
S Ogata ◽  
A Miki ◽  
T Kominami
Keyword(s):  
Alkaline Phosphatase ◽  
Phospholipase C ◽  
Plasma Membranes ◽  
Polyacrylamide Gel Electrophoresis ◽  
Gel Filtration ◽  
Soluble Form ◽  
Microsomal Membranes ◽  
Hydrophobic Nature ◽  
Rat Hepatoma

A major glycoprotein of rat hepatoma plasma membranes was selectively released as a soluble form by incubating the membrane with phosphatidylinositol-specific phospholipase C. The soluble form corresponding to the glycoprotein was also prepared by butan-1-ol extraction of microsomal membranes at pH 5.5, whereas extraction at pH 8.5 yielded an electrophoretically different form with a hydrophobic nature. The soluble glycoprotein extracted at pH 5.5 was purified by sequential chromatography on concanavalin A-Sepharose, Sephacryl S-300 and anti-(alkaline phosphatase) IgG-Sepharose, the last step being used to remove a contaminating alkaline phosphatase. The glycoprotein thus purified was a single protein with Mr 130,000 in SDS/polyacrylamide-gel electrophoresis, although it behaved as a dimer in gel filtration on Sephacryl S-300. The glycoprotein was analysed for amino acid and carbohydrate composition. The composition of the carbohydrate moiety, which amounted to 64% by weight, suggested that the glycoprotein contained much larger numbers of N-linked oligosaccharide chains than those with O-linkage. It was confirmed that the purified glycoprotein was immunologically identical not only with that released by the phospholipase C but also with the hydrophobic form extracted with butan-1-ol at pH 8.5. The results indicate that the glycoprotein of rat hepatoma plasma membranes, which has an unusually high content of carbohydrate, is another membrane protein released by phosphatidylinositol-specific phospholipase C, as documented for alkaline phosphatase, acetylcholinesterase and Thy-1 antigen.

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