Effect of phosphatidylinositol and phosphatidylserine on membrane-bound galactosyltransferase

1980 ◽  
Vol 58 (1) ◽  
pp. 58-66 ◽  
Author(s):  
Samuel Ratnam ◽  
Ian H. Fraser ◽  
Sailen Mookerjea
Keyword(s):  
Enzyme Activity ◽  
Phosphatidyl Serine ◽  
High Concentration ◽  
Electron Microscopic ◽  
Membrane Solubilization ◽  
Wide Range ◽  
Biphasic Effect ◽  
Solubilized Enzyme ◽  
Membrane Bound ◽  
Triton X

Membrane-bound galactosyltransferase is solubilized and activated by exogenous lysolecithin or Triton X-100. A study on the effect of different phospholipids on the lysolecithin-solubilized enzyme showed that two charged phospholipids (i.e., phosphatidylinositol and phosphatidyl-serine) inhibited the membrane-bound enzyme in the presence of a wide range of lysolecithin concentration (up to 6 μmol/mg protein). In contrast, these phospholipids produced a biphasic effect on the enzyme solubilized with Triton X-100. In lower concentration of Triton (up to 2 μmol/mg protein), the charged phospholipids somewhat reduced the enzyme activity but a reversal of this effect was observed when Triton concentration was gradually raised (from 2 to 8 μmol/mg protein). This biphasic effect of the phospholipids was also demonstrated on purified membrane-bound galactosyltransferase in presence of low and high concentration of Triton. Electron microscopic evidence suggested that an increased concentration of phosphatidylinositol prevented membrane solubilization by lysolecithin or retained the membrane vesicular organization concurrent with a restraining effect on the enzyme. The results lend support to the hypothesis that the phospholipid microenvironment of the membrane may exert a control on the membrane-bound glycosyltransferases.

Synaptosomal Na+,K+-ATPase as a membrane probe in studying the in vivo action of morphine

1981 ◽  
Vol 59 (8) ◽  
pp. 687-692 ◽  
Author(s):  
Ophelia Wan-Kan ◽  
E. A. Hosein
Keyword(s):  
Activation Energy ◽  
Enzyme Activity ◽  
Transition Temperature ◽  
Specific Activity ◽  
Membrane Phospholipids ◽  
Membrane Probe ◽  
Biphasic Effect ◽  
Brain Synaptosomes ◽  
Membrane Bound

The activity of membrane-bound Na+,K+-ATPase was used as a metabolic probe to study the effects of morphine in vivo in rat brain synaptosomes. Arrhenius plots were generated to study an induced perturbation within the membrane. In acute studies 0.5-h postmorphine, the drug was without effect on the basal activity of the enzyme. With dopamine-stimulated Na+,K+-ATPase morphine decreased the apparent transition temperature and specific activity of the enzyme while there was a slight stimulation in its activation energy. An increase in these parameters was observed in samples taken from animals withdrawn from the drug for 48 h. These results strongly suggest the possible involvement of the membrane phospholipids as transducer which mediates the observed biphasic effect of the drug on enzyme activity.

scholarly journals Physical and kinetic properties of a plasma-membrane-bound β-d-glucosidase (cellobiase) from midgut cells of an insect (Rhynchosciara americana larva)

1983 ◽  
Vol 213 (1) ◽  
pp. 43-51 ◽  
Author(s):  
C Ferreira ◽  
W R Terra
Keyword(s):  
Plasma Membrane ◽  
Gradient Centrifugation ◽  
Soluble Form ◽  
Kinetic Properties ◽  
Carbonium Ion ◽  
Wide Range ◽  
Catalytic Constant ◽  
Rhynchosciara Americana ◽  
Membrane Bound ◽  
Triton X

The midgut caecal cells from Rhynchosciara americana larvae possess a plasma-membrane-bound beta-D-glucosidase (cellobiase, EC 3.2.1.21), which is recovered (75-95%) in soluble form both after treatment with Triton X-100 and after treatment with papain. The Triton X-100-solubilized beta-D-glucosidase displays Mr106000 and pI 5.4, whereas the papain-released beta-D-glucosidase shows Mr65000 and pI 4.7. Thermal inactivations of the detergent-solubilized and the papain-released forms of beta-D-glucosidase both follow apparent first-order kinetics with similar half-lives. The papain-released beta-D-glucosidase, after being purified by density-gradient centrifugation, hydrolyses beta-D-glucosides, beta-D-galactosides and beta-D-fucosides at the same active site, as inferred from experiments of competition between substrates. The beta-D-glucosidase seems to operate in accordance with rapid-equilibrium kinetics, since the Km (0.61 mM) for the enzyme is constant over a wide range of pH. The hydrolysis of the beta-D-glucosidic bond catalysed by the beta-D-glucosidase occurs without inversion of configuration, delta-gluconolactone is a strong (Ki 0.5 microM) inhibitor of the enzyme and substituents in the substrate aglycone affect the catalytic constant of the reaction. These data support the assumption that the mechanism of the reaction catalysed by the beta-D-glucosidase involves the intermediary formation of a carbonium ion, rather than a glucosyl-enzyme intermediate.

scholarly journals Direct desaturation of intact galactolipids by a desaturase solubilized from spinach (Spinacia oleracea) chloroplast envelopes

1993 ◽  
Vol 289 (3) ◽  
pp. 777-782 ◽  
Author(s):  
H Schmidt ◽  
E Heinz
Keyword(s):  
Double Bond ◽  
Spinacia Oleracea ◽  
Membrane Lipids ◽  
Fatty Acyl ◽  
Acyl Residue ◽  
Solubilized Enzyme ◽  
Membrane Bound ◽  
Triton X ◽  
Envelope Membranes

In plants, polyenoic fatty acids are synthesized by desaturase enzymes which use acyl groups of membrane lipids as substrates. To provide direct ‘in vitro’ evidence for this reaction, we solubilized envelope membranes from spinach (Spinacia oleracea) chloroplasts with Triton X-100 to release a membrane-bound n-6 desaturase. In the presence of oxygen and reduced ferredoxin, the solubilized enzyme desaturated a variety of substrates, such as free oleic acid, free erucic acid, 1-oleoyl-sn-glycerol 3-phosphate and the three galactolipids 1-oleoyl-2-(7′-cis-hexadecenoyl)-3-beta-D-galactopyranosyl-sn-glycerol, 1,2-dioleoyl-3-beta-D-galactopyranosyl-sn-glycerol and the ether analogue 1,2-di-(9′-cis-octadecenyl)-3-beta-D-galactopyranosyl-sn- glycerol. The in vitro desaturation of these exogenously added complex lipids with ester- and ether-linked substrate chains is unambiguous evidence for lipid-linked desaturation. The enzyme measures the insertion of the new double bond from the methyl end and the existing (n-9)-cis-double bond of an appropriate acyl or alkyl chain. The distal part of the substrate group, normally the carboxy end of a fatty acyl residue, is of less importance and, in particular, its activation in thioester form is not required.

An Electron Microscopic Study of the Acute Effects of Hypothalamic Releasing Factors on the Anterior Pituitary Gland

1968 ◽  
Vol 26 ◽  
pp. 232-233
Author(s):  
P.W. Coates ◽  
E.A. Ashby ◽  
L. Krulich ◽  
A. Dhariwal ◽  
S. McCann
Keyword(s):  
Anterior Pituitary ◽  
Microscopic Investigation ◽  
Uranyl Acetate ◽  
Electron Microscopic Investigation ◽  
Electron Microscopic ◽  
Tissue Samples ◽  
Thin Sections ◽  
Dense Membrane ◽  
Membrane Bound ◽  
Releasing Factors

The morphologic effects on somatotrophs of crude sheep hypothalamic extract prepared from stalk-median eminence were studied by electron microscopy in conjunction with concurrently run bioassays performed on the same tissue samples taken from young adult male Sherman rats.Groups were divided into uninjected controls and injected experimentals sacrificed at 5', 15', and 30' after injection. Half of each anterior pituitary was prepared for electron microscopic investigation, the other half for bioassay. Fixation using collidine buffered osmium tetroxide was followed by dehydration and embedment in Maraglas. Uranyl acetate and lead citrate were used as stains. Thin sections were examined in a Philips EM 200.Somatotrophs from uninjected controls appeared as described in the literature (Fig. 1). In addition to other components, these cells contained moderate numbers of spherical, electron-dense, membrane-bound granules approximately 350 millicrons in diameter.

Microscopic investigations of novel intracellular bodies of a Nocardia SP

1994 ◽  
Vol 52 ◽  
pp. 356-357
Author(s):  
J. L. Stites
Keyword(s):  
Uranyl Acetate ◽  
Electron Microscopic ◽  
En Bloc ◽  
Ribonucleic Acids ◽  
Transmission Electron ◽  
Nocardia Sp ◽  
Internal Constitution ◽  
Membrane Bound ◽  
Molecular Components ◽  
Protein Rich

A Nocardia sp.was found during an initial transmission electron microscopic (TEM) examination to have unusual intracellular bodies (ICB's) which do not appear to have been described previously in the literature. Most intracellular structures within bacteria have been classified as storage granules, a product of membrane invagination (i.e. mesosomes), or vacuoles. In bacteria there are no known intracellular membrane-bound organelles, and all internal membranes are invaginations of the unit membrane. Several microscopic-level examinations of the Nocardia sp. ICB's were initiated in order to determine their overall structure, classification, and internal constitution.Different TEM staining procedures were performed to determine possible molecular components of the ICB. In all of the staining protocols the ICB's showed a lack of electron density similar to the cell wall. Because the ICB's showed no affinity to any stain, it appeared they do not have strong positive charge (phosphotungstic acid), are not protein rich (en bloc uranyl acetate), lack glycogen and are not phosphate or sulphur rich (lead citrate), nor do they contain lipids or ribonucleic acids (osmium tetroxide).

Ultrastructural Study of Apocrine Differentiation in Human Mammary Carcinoma: Correlation of Granule Content With Sex Steroid Binding

1980 ◽  
Vol 38 ◽  
pp. 742-743
Author(s):  
S. E. Levine ◽  
A. D. Brinkhous ◽  
K. S. McCarty ◽  
J. A. Mossier ◽  
K.S. McCarty
Keyword(s):  
Ultrastructural Study ◽  
Ductal Carcinoma ◽  
Apocrine Carcinoma ◽  
Electron Microscopic ◽  
Granular Eosinophilic Cytoplasm ◽  
Eosinophilic Cytoplasm ◽  
Apocrine Differentiation ◽  
Microscopic Features ◽  
Membrane Bound ◽  
Epithelial Lesions

A variant of ductal carcinoma of the human breast which has been designated apocrine carcinoma has distinctive light and electron microscopic features. Such tumors comprise approximately 0.5% of breast carcinomas. Abundant cytoplasmic membrane bound vesicles (400-600 nm) with dense homogeneous osmophilic cores characterize these tumors. These granules are also seen in apocrine metaplastic breast epithelial lesions1 and appear to be responsible for the finely granular eosinophilic cytoplasm observed by light microscopy. A high content of intermediate affinity non-saturable 4S progesteroneestrogen binding protein (PEBP) in apocrine carcinoma has been reported.2 The present ultrastructural study evaluates the presence of apocrine granules in infiltrating ductal carcinoma (NOS) to determine if a correlation exists between apocrine granule content and the quantity of PEBP present.

Exterior and Interior Events in Early Stage of Thrombin-induced Platelet Aggregation

1977 ◽  
Vol 38 (03) ◽  
pp. 0630-0639 ◽  
Author(s):  
Shuichi Hashimoto ◽  
Sachiko Shibata ◽  
Bonro Kobayashi
Keyword(s):  
Molecular Weight ◽  
Enzyme Activity ◽  
Plasma Membrane ◽  
Platelet Aggregation ◽  
Early Stage ◽  
Adenyl Cyclase ◽  
Cellular Component ◽  
Primary Event ◽  
Rabbit Platelets ◽  
Membrane Bound

SummaryTreatment of washed rabbit platelets with 1 u/ml of thrombin at 37° C resulted in a disappearance from platelets of a protein with 250,000 dalton molecular weight which was shown to be originated from plasma membrane. Parallel loss of adenyl cyclase was noted, and both reactions were complete within 30 sec. From the patterns of disc electrophoretograms, the importance of quick suppression of thrombin action in demonstrating the primary event was stressed.Thrombin induced an apparent activation of membrane bound phosphodiesterase. This reaction was also complete within 30 sec. The cellular component which contained the enzyme activity was distinct from plasma membrane. Soluble phosphodiesterase was not influenced by thrombin at all.These reactions required intact platelet cells to react with thrombin, and no reaction was detected when subcellular preparations were treated with thrombin.Possibility of collaboration of changes in externally located synthetic enzyme with those in internally located degrading enzyme in the early phase of thrombin action on platelets was suggested.

Wetting of glass surface using natural surfactants

2020 ◽  
Vol 12 ◽  
Author(s):  
Nihar Ranjan Biswal
Keyword(s):  
Contact Angle ◽  
Glass Surface ◽  
Pure Water ◽  
Amyl Alcohol ◽  
Synthetic Surfactant ◽  
Wide Range ◽  
Different Types ◽  
Natural Surfactants ◽  
Triton X ◽  
Solid Liquid

Background: Surfactant adsorption at the interfaces (solid–liquid, liquid–air, or liquid–liquid) is receiving considerable attention from a long time due to its wide range of practical applications. Objective: Specifically wettability of solid surface by liquids is mainly measured by contact angle and has many practical importances where solid–liquid systems are used. Adsorption of surfactants plays an important role in the wetting process. The wetting behaviours of three plant-based natural surfactants (Reetha, Shikakai, and Acacia) on the glass surface are compared with one widely used nonionic synthetic surfactant (Triton X-100) and reported in this study. Methods: The dynamic contact angle study of three different types of plant surfactants (Reetha, Shikakai and Acacia) and one synthetic surfactant (Triton X 100) on the glass surface has been carried out. The effect of two different types of alcohols such as Methanol and amyl alcohol on wettability of shikakai, as it shows little higher value of contact angle on glass surface has been measured. Results: The contact angle measurements show that there is an increase in contact angle from 47° (pure water) to 67.72°, 65.57°, 68.84°, and 68.79° for Reetha, Acacia, Shikakai, and Triton X-100 respectively with the increase in surfactant concentration and remain constant at CMC. The change in contact angle of Shikakai-Amyl alcohol mixtures are slightly different than that of methanol-Shikakai mixture, mostly there is a gradual increase in contact angle with the increasing in alcohol concentration. Conclusion: There is no linear relationship between cos θ and inverse of surface tension. There was a linear increase in surface free energy results with increase in concentration as more surfactant molecules were adsorbing at the interface enhancing an increase in contact angle.

Effect of nitric oxide on Sertoli cell microtubule of piglets

2009 ◽  
Vol 6 (3) ◽  
pp. 257-263 ◽  
Author(s):  
Yang Li ◽  
Wang Xian-zhong ◽  
Yang Meng-bo ◽  
Zhang Jia-hua
Keyword(s):  
Nitric Oxide ◽  
Enzyme Activity ◽  
Protein Kinase ◽  
Cell Viability ◽  
Sodium Nitroprusside ◽  
Sertoli Cell ◽  
Sertoli Cells ◽  
High Concentration ◽  
Treatment Results ◽  
Anti Oxidant

AbstractTo illustrate the effect of nitric oxide (NO) on the microtubules of Sertoli cells (SC), SCs of piglets were treated with sodium nitroprusside (SNP). Changes in cell viability, anti-oxidant activity, enzyme activity and p38 mutagen-activated protein kinase (p38MAPK) activation were detected. The results were as follows. A low concentration of NO can keep SC microtubule and cell viability normal, and a high concentration of NO could increase p38MAPK activation, decrease anti-oxidant activity and transferrin secretion, and destroy the structure and distribution of the microtubules. The results suggest that SNP treatment results in an increase in NO in SCs and decreased cell anti-oxidant activity. The high concentration of NO destroys cell microtubules by activating p38MAPK.

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