scholarly journals External labelling of glycoproteins from first-trimester human placental microvilli

1984 ◽  
Vol 221 (3) ◽  
pp. 821-828 ◽  
Author(s):  
S J Fisher ◽  
M S Leitch ◽  
R A Laine
Keyword(s):  
Molecular Mass ◽  
Brush Border ◽  
Plasma Membranes ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
First Trimester ◽  
Galactose Oxidase ◽  
Reducing Conditions ◽  
A Minor

The brush-border glycoproteins of first-trimester human placentas were investigated by using two external labelling techniques: (1) sequential digestion with neuraminidase and galactose oxidase, followed by reduction with NaB3H4, which 3H-labels terminal galactose and galactosamine residues; and (2) sequential treatment with periodate and NaB3H4, which 3H-labels terminal sialic acid residues. The labelling procedures were performed on intact tissue so that the results would more closely approximate the topography of the brush border in vivo. The microvilli were isolated, subjected to sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, and the [3H]glycoproteins detected by fluorography. Densitometer scans of the fluorograms of the [3H]galactoproteins showed that, under reducing conditions, 90% of the protein-associated radioactivity was incorporated into two glycoproteins. The major [3H]galactoprotein of early placental microvilli had an estimated molecular mass of 92 kDa (desialylated) and migrated as a diffuse band. A minor 180 kDa glycoprotein was less consistently labelled. No change in the apparent molecular mass of either component was detected in the absence of beta-mercaptoethanol, suggesting that the 180 kDa component was not a dimer of the 92 kDa glycoprotein. The remaining 10% the radioactivity was equally distributed among several minor membrane components. Densitometer scans of the fluorograms of the [3H]sialoproteins showed that, under either reducing or non-reducing conditions, 90% of the 3H was preferentially incorporated into the 92-110 kDa region of the gel. Although no distinct bands were visible, the higher-molecular-mass region of this area was always most heavily labelled. A minor 180 kDa glycoprotein was also 3H-labelled. The pattern of brushborder [3H]glycoproteins from first-trimester placentas differed markedly from that of term placental microvilli and from placental fibroblast plasma membranes that were 3H-labelled by identical external labelling techniques. These results indicate that: (1) the glycoprotein determinants of brush-border topography change during pregnancy; (2) within the placenta, the major 92 kDa (desialylated) determinant, which has not been previously described, is unique to the trophoblastic cells.

scholarly journals Detection of Schistosoma mansoni Membrane Antigens by Immunoblot Analysis of Sera of Patients from Low-Transmission Areas

2005 ◽  
Vol 12 (2) ◽  
pp. 280-286 ◽  
Author(s):  
Italo M. Cesari ◽  
Diana E. Ballen ◽  
Leydi Mendoza ◽  
César Matos
Keyword(s):  
Schistosoma Mansoni ◽  
Molecular Mass ◽  
Polyacrylamide Gel Electrophoresis ◽  
Surface Membrane ◽  
Sodium Dodecyl ◽  
Mass Range ◽  
Confirmatory Test ◽  
Low Transmission ◽  
Membrane Antigens

ABSTRACT Schistosoma mansoni surface membrane components play a relevant role in the host-parasite interaction, and some are released in vivo as circulating antigens. n-Butanol extraction favors the release of membrane antigens like alkaline phosphatase, which has been shown to be specifically recognized by antibodies from S. mansoni-infected humans and animals. In the present study, components in the n-butanol extract (BE) of the adult S. mansoni worm membrane fraction were separated by one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (1D SDS-PAGE [15%]) and further analyzed by immunoblotting (immunoglobulin G) using defined sera. S. mansoni-infected patient sera, but not sera of uninfected patients or sera obtained from patients infected with other parasite species, specifically and variably recognized up to 20 polypeptides in the molecular mass range of ∼8 to >80 kDa. There were some differences in the number, intensity, and frequency of recognition of the BE antigens among sera from Venezuelan sites of endemicity with a different status of schistosomiasis transmission. Antigens in the 28- to 24-kDa molecular mass range appeared as immunodominants and were recognized by S. mansoni-positive sera from all the sites, with recognition frequencies varying between 57.5 and 97.5%. Immunoblotting with BE membrane antigens resulted in a highly sensitive (98.1%), specific (96.1.0%), and confirmatory test for the immunodiagnosis of schistosomiasis in low-transmission areas.

scholarly journals Complex-formation and inhibition of urokinase by blood plasma proteins

1983 ◽  
Vol 215 (1) ◽  
pp. 123-131 ◽  
Author(s):  
E K Waller ◽  
W D Schleuning ◽  
E Reich
Keyword(s):  
Complex Formation ◽  
Rate Constant ◽  
Plasma Proteins ◽  
Proteinase Inhibitors ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Order Rate Constant ◽  
Reducing Conditions ◽  
Blood Plasma Proteins

We have studied the formation of covalent complexes between 125I-urokinase (125I-UK) and proteins in human plasma. Although 125I-UK reacts with many proteinase inhibitors in purified systems, the predominant complexes formed in plasma are with antithrombin III (ATIII) and alpha 2-macroglobulin (alpha 2M). 125I-UK interacts with purified alpha 2M or alpha 2M in plasma to form a characteristic pattern of multiple complexes whose Mr values by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis are in the range of 380 000-720 000, under non-reducing conditions, and 180 000-430 000 after reduction. We also examined the inhibition of UK amidolytic activity by plasma and by purified ATIII. In the presence of saturating concentrations of ATIII and heparin, an apparent first-order rate constant of 6.8 X 10(-1) s-1 was calculated for the inhibition of urokinase. In contrast, the rate constant for the formation of covalent ATIII-UK complexes was lower, suggesting the inhibition of UK proceeds first via the formation of transient non-covalent intermediates that are then transformed more slowly into covalent end products. The observed rate constants for enzyme inhibition or complex-formation with plasma or purified inhibitors are insufficient to account for the reported clearance rate of injected UK in vivo.

scholarly journals Molecular Characterization of the Plasma Membrane H+-ATPase, an Antifungal Target inCryptococcus neoformans

2000 ◽  
Vol 44 (9) ◽  
pp. 2349-2355 ◽  
Author(s):  
Patricia Soteropoulos ◽  
Tanya Vaz ◽  
Rosaria Santangelo ◽  
Padmaja Paderu ◽  
David Y. Huang ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Molecular Mass ◽  
Plasma Membranes ◽  
Atp Hydrolysis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Proton Pumps ◽  
Gene Encoding ◽  
Reading Frame ◽  
Whole Cells

ABSTRACT The Cryptococcus neoformans PMA1 gene, encoding a plasma membrane H+-ATPase, was isolated from a genomic DNA library of serotype A strain ATCC 6352. An open reading frame of 3,380 nucleotides contains six introns and encodes a predicted protein consisting of 998 amino acids with a molecular mass of approximately 108 kDa. Plasma membranes were isolated, and the H+-ATPase was shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to be slightly larger than the S. cerevisiaeH+-ATPase, consistent with its predicted molecular mass. The plasma membrane-bound enzyme exhibited a pH 6.5 optimum for ATP hydrolysis, Km and V maxvalues of 0.5 mM and 3.1 μmol mg−1 min−1, respectively, and an apparent Ki for vanadate inhibition of 1.6 μM. ATP hydrolysis in plasma membranes and medium acidification by whole cells were inhibited by ebselen, a nonspecific H+-ATPase antagonist which was also fungicidal. The predicted C. neoformans protein is 35% identical to proton pumps of both pathogenic and nonpathogenic fungi but exhibits more than 50% identity to PMA1 genes from plants. Collectively, this study provides the basis for establishing the CryptococcusH+-ATPase as a viable target for antifungal drug discovery.

Protein digestion in human and rat small intestine: role of new neutral endopeptidases

1988 ◽  
Vol 255 (2) ◽  
pp. G212-G220 ◽  
Author(s):  
D. Guan ◽  
M. Yoshioka ◽  
R. H. Erickson ◽  
W. Heizer ◽  
Y. S. Kim
Keyword(s):  
Brush Border ◽  
Brush Border Membrane ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Biochemical Properties ◽  
Intact Protein ◽  
Human Intestine ◽  
Protein Digestion ◽  
Small Molecular Weight

Two new phosphoramidon-insensitive neutral endopeptidases were identified and partially characterized in the brush-border membrane of rat and human intestine using N-CBZ-L-Ala-L-Arg-L-Arg-4-methoxy-beta-naphthylamide (Z-Ala-Arg-Arg-MNA) and azocasein or alpha-casein as substrates. Activities in the brush-border membrane of both rat and human intestine were maximum at neutral to alkaline pH, were inhibited by metal chelating and thiol reagents, and were insensitive to phosphoramidon. The results also indicate that these endopeptidases are distinct from pancreatic proteases. The biochemical properties of the enzyme hydrolyzing Z-Ala-Arg-Arg-MNA were shown to be different from that hydrolyzing azocasein or alpha-casein. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration revealed that several native intact protein substrates were rapidly degraded to small molecular weight peptides and amino acids when incubated with rat or human brush-border membrane preparations. During in vivo intestinal perfusion in rats, 11% of the total administered alpha-casein was hydrolyzed and absorbed by the intestine. The results suggest that phosphoramidon-insensitive endopeptidases in the intestinal brush-border membrane may be of nutritional and physiological importance in protein digestion.

scholarly journals The Ly-3 antigens on mouse thymocytes: immune precipitation and molecular weight characterization.

1976 ◽  
Vol 144 (2) ◽  
pp. 476-493 ◽  
Author(s):  
P J Durda ◽  
P D Gottlieb
Keyword(s):  
Molecular Weight ◽  
Gel Electrophoresis ◽  
Genetic Linkage ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Galactose Oxidase ◽  
Reducing Conditions ◽  
Sds Page ◽  
Immune Precipitation ◽  
Peptide Marker

Specific anti-Ly sera were employed to precipitate Ly antigens from Nonidet P-40 extracts of mouse thymocytes labeled with 125I using lactoperoxidase and with NaB3H4 using galactose oxidase. Thymocytes from mice of the congenic strains C57BL/6J (Ly-2.2, Ly-3.2 positive), C57BL/6Ly-2a, Ly-3a (Ly-2.1, Ly-3.1 positive) and C57BL/6-Ly-2a (Ly-2.1, Ly-3.2-positive) were used as sources of labeled antigens and as immune adsorbants to permit evaluation of the specificity of each anti-Ly serum employed. Results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing conditions are consistent with the Ly-3.1 antigen containing a glycoprotein subunit with an apparent mol wt of 35,000 daltons. Specific precipitates obtained using anti-Ly-2.1 serum yielded SDS-PAGE profiles identical to that obtained with anti-Ly-3.1 serum, suggesting that the Ly-2 and Ly-3 antigens have the same molecular weight distribution. The relationships of these results to the observed close genetic and topological linkage of Ly-2 and Ly-3 and to the genetic linkage of these loci with the IB-peptide marker, a mouse Bk-region polymorphism, are discussed.

scholarly journals Studies on rat liver plasma membrane. Altered protein and phospholipid metabolism after injection of d-galactosamine

1977 ◽  
Vol 166 (3) ◽  
pp. 455-462 ◽  
Author(s):  
W Bachmann ◽  
E Harms ◽  
B Hassels ◽  
H Henninger ◽  
W Reuitter
Keyword(s):  
Plasma Membrane ◽  
Rat Liver ◽  
Plasma Membranes ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Protein Composition ◽  
Phospholipid Metabolism ◽  
Morphological Alterations ◽  
Galactosamine Hepatitis

1. The metabolism of protein and phospholipid in rat liver plasma membranes isolated by the method of Neville [(1960) J. Biophys. Biochem. Cytol. 8, 413-422] was investigated 3 and 6 h after the injection of D-galactosamine in vivo. During this time, all the biochemical and morphological alterations associated with hepatitis developed. 2. After the injection of D-galactosamine the concentration of sphingomyelin in the plasma membrane decreased to below 60% of the control values. 3. The activity of 5′-nucleotidase (EC 3.1.3.5), which has been purified as a sphingomyelin-protein complex, decreased in the total homogenate as well as in the plasma-membrane fraction of livers of rats treated with galactosamine, to about 60% of the control values. 4. Protein synthesis, as measured by the incorporation of [14C]leucine into plasma membranes, was decreased to 45% of that of the controls. However, only small differences were observed in the amino acid composition of the plasma membrane after D-galactosamine treatment. 5. The protein composition of the plasma membranes was determined by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. The results showed a change from low- to high-molecular-weight proteins after the injection of galactosamine. 6. These results demonstrate different metabolic processes of the plasma membrane altered during the induction of galactosamine hepatitis.

Glycogen phosphorylase in fish muscle: demonstration of three interconvertible forms

1990 ◽  
Vol 258 (2) ◽  
pp. C344-C351 ◽  
Author(s):  
H. Schmidt ◽  
G. Wegener
Keyword(s):  
Glycogen Phosphorylase ◽  
Specific Activity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Muscular Activity ◽  
Fish Muscle ◽  
Kinetic Properties ◽  
Phosphorylase Activity ◽  
Tissue Extracts

White skeletal muscle of crucian carp contains a single isoenzyme of glycogen phosphorylase, which was purified approximately 300-fold to a specific activity of approximately 13 mumol.min-1.mg protein-1 (assayed in the direction of glycogen breakdown at 25 degrees C). Tissue extracts of crucian muscle produced three distinct peaks of phosphorylase activity when separated on DEAE-Sephacel. Peaks 1 and 3 were identified, in terms of kinetic properties and by interconversion experiments, as phosphorylase b and a, respectively. Peak 2 was shown to be a phospho-dephospho hybrid. The three interconvertible forms of phosphorylase were purified and shown to be dimeric molecules at 20 degrees C. At 5 degrees C, a and the hybrid tended to form tetramers. The Mr of the subunit was estimated to be 96,400 from sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The hybrid is kinetically homogeneous, and its kinetic properties are intermediate between those of b and a forms. The b, hybrid, and a forms of phosphorylase can be isolated from rapidly frozen muscle of crucian but in different proportions, depending on whether fish were anesthetized or forced to muscular activity for 20 s. Muscle of anesthetized crucian had 36, 36, and 28% of phosphorylase b, hybrid, and a forms, respectively, whereas the corresponding values for exercised fish were 12, 37, and 51%. Results suggest that three interconvertible forms of phosphorylase exist simultaneously in crucian muscle and that hybrid phosphorylase is active in contracting muscle in vivo.

A metalloproteinase extracellularly released byCrithidia deanei

2003 ◽  
Vol 49 (10) ◽  
pp. 625-632 ◽  
Author(s):  
Claudia Masini d'Avila-Levy ◽  
Rodrigo F Souza ◽  
Rosana C Gomes ◽  
Alane B Vermelho ◽  
Marta H Branquinha
Keyword(s):  
Molecular Mass ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Gel Filtration ◽  
Residual Activity ◽  
Major Protein ◽  
Motile Cells ◽  
Sds Page ◽  
Triton X

Actively motile cells from a cured strain of Crithidia deanei released proteins in phosphate buffer (pH 7.4). The molecular mass of the released polypeptides, which included some proteinases, ranged from 19 to 116 kDa. One of the major protein bands was purified to homogeneity by a combination of anion-exchange and gel filtration chromatographs. The apparent molecular mass of this protein was estimated to be 62 kDa by sodium dodecyl sulfate – polyacrylamide gel electrophoresis (SDS–PAGE). The incorporation of gelatin into SDS–PAGE showed that the purified protein presented proteolytic activity in a position corresponding to a molecular mass of 60 kDa. The enzyme was optimally active at 37 °C and pH 6.0 and showed 25% of residual activity at 28 °C for 30 min. The proteinase was inhibited by 1,10-phenanthroline and EDTA, showing that it belonged to the metalloproteinase class. A polyclonal antibody to the leishmanial gp63 reacted strongly with the released C. deanei protease. After Triton X-114 extraction, an enzyme similar to the purified metalloproteinase was detected in aqueous and detergent-rich phases. The detection of an extracellular metalloproteinase produced by C. deanei and some other Crithidia species suggests a potential role of this released enzyme in substrate degradation that may be relevant to the survival of trypanosomatids in the host.Key words: endosymbiont, trypanosomatid, extracellular, proteinase.

Functional specificity of jejunal brush-border pteroylpolyglutamate hydrolase in pig

1991 ◽  
Vol 260 (6) ◽  
pp. G865-G872 ◽  
Author(s):  
C. J. Chandler ◽  
D. A. Harrison ◽  
C. A. Buffington ◽  
N. A. Santiago ◽  
C. H. Halsted
Keyword(s):  
Brush Border ◽  
Protein Band ◽  
Major Protein ◽  
Functional Specificity ◽  
Major Protein Band ◽  
Regional Location ◽  
Minor Protein ◽  
A Minor ◽  
Hydrolysis Of

To determine the functional specificity of intestinal brush-border pteroylpolyglutamate hydrolase (PPH), we compared the regional location of in vivo hydrolysis of pteroyltriglutamate (PteGlu3) with the location of activity and immunoreactivity of the enzyme in the pig. After in vivo incubations, PteGlu3 hydrolytic products were recovered from intestinal segments in the jejunum but not from the ileum. Brush-border PPH activity in fractionated mucosa was 10-fold greater in the jejunum than in the ileum, whereas the activity of intracellular PPH was increased in the distal ileum. Antibodies to purified brush-border PPH identified a major protein band at 120 kDa and a minor protein band at 195 kDa in solubilized jejunal brush border. Immunohistochemistry identified the enzyme only on the brush-border surface of the jejunum, whereas an immunoblot of solubilized brush-border membranes identified brush-border PPH in the jejunum but not in the ileum. The parallel of the regional location of in vivo hydrolysis of PteGlu3 with the location of brush-border PPH activity and immunoreactivity demonstrates the functional specificity of this enzyme in folate digestion.

scholarly journals Photoaffinity labelling of a nitrobenzylthioinosine-binding polypeptide from cultured Novikoff hepatoma cells

1986 ◽  
Vol 236 (3) ◽  
pp. 665-670 ◽  
Author(s):  
W P Gati ◽  
J A Belt ◽  
E S Jakobs ◽  
J D Young ◽  
S M Jarvis ◽  
...  
Keyword(s):  
Gel Electrophoresis ◽  
Plasma Membranes ◽  
Specific Binding ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Hepatoma Cells ◽  
Nucleoside Transport ◽  
Facilitated Diffusion ◽  
Animal Cells ◽  
Novikoff Hepatoma

Site-specific binding of nitrobenzylthioinosine (NBMPR) to plasma membranes of some animal cells results in the inhibition of the facilitated diffusion of nucleosides. The present study showed that nucleoside transport in Novikoff UA rat hepatoma cells is insensitive to site-saturating concentrations of NBMPR. Equilibrium binding experiments demonstrated the presence of high-affinity sites for NBMPR in a membrane-enriched fraction from these cells. In the presence of uridine or dipyridamole, specific binding of NBMPR at these sites was inhibited. When Novikoff UA membranes were covalently labelled with [3H]NBMPR by using photoaffinity techniques, specifically bound radioactivity was incorporated exclusively into a polypeptide(s) with an apparent Mr of 72,000-80,000, determined by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. Covalent labelling of this polypeptide was abolished in the presence of excess nitrobenzylthioguanosine (NBTGR) and reduced in the presence of adenosine, uridine or dipyridamole. The apparent Mr of the NBMPR-binding polypeptide in Novikoff UA cells is significantly higher than that reported for corresponding polypeptides in other cell types (Mr 45,000-66,000). When membrane-enriched preparations from S49 mouse lymphoma cells were photolabelled and mixed with labelled NovikoffUA membrane-enriched preparations, gel electrophoresis resolved the NBMPR-binding polypeptides from the two preparations.

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