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Biomedical subjects

R Bourrillon

Publications and source records attributed to R Bourrillon.

At least 37 records · Page 2Linked to original sources
PubMed1982

Purification and characterization of a major cell surface glycoprotein in Zajdela ascites hepatoma cells which displays a potent concanavalin A receptor activity.

A major cell surface sialoglycoprotein with Concanavalin A receptor activity has been isolated from rat Zajdela ascites hepatoma cells. The sialic acid residues of the plasma membrane glycoproteins were specifically labeled by oxidation and NaIO4 followed by reduction with NaB3H4. Surface-labeled glycoproteins were released by short incubations with TPCK-trypsin at 37 degrees C and then separated by gel filtration on Sepharose 6B column. The predominantly labeled fraction, GP II2, was then purified by chromatography on DEAE-cellulose equilibrated with 0.05 M phosphate buffer, pH 7.5, and eluted with increasing molarities of NaCl. It was shown to be homogeneous by protein and carbohydrate staining on SDS-polyacrylamide gels, isoelectric focusing, rechromatography on DEAE-cellulose and immunoelectrophoresis. It has an apparent molecular weight of 110,000 daltons. The location of GP II2 on the cell surface was confirmed by the fact that it could be labeled metabolically with D-(3H) glucosamine and externally through the nonpenetrating periodate-NaB3H4 system. GP II2 could not be removed from the cell surface by high salt concentrations, chelator, or chaotropic agents but was released from the membrane by detergents. This suggests that GP II2 could be an integral protein. Analysis of the carbohydrate composition of GP II2 revealed galactose, N-acetylglucosamine, N-acetylgalactosamine, and sialic acid as major constituents and mannose as a minor one. This suggests that it contains carbohydrate chains both O- and N-linked to the polypeptide chain, most of them being O-linked. Finally, GP II2 has a potent Concanavalin A receptor activity. It inhibits the interaction between Concanavalin A and hepatoma cells and suppresses its effects on hepatoma cell proliferation.

Animals↗
PubMed1981

Cryoinsolubility of peanut agglutinin. Effect of saccharides and neutral salts.

Peanut agglutinin (PNA) has been shown to be insoluble at low temperatures. This cryoinsolubility has been studied by means of absorption spectroscopy, fluorescence, circular dichroism, and analytical ultracentrifugation. It was found to be dependent on pH, temperature, and protein concentration. No effects on dimer-tetramer equilibrium could be determined nor any conformational changes provoked by exposure of the PNA preparation to low temperatures. The dimer half-molecule apparently does not precipitate. The cryoinsolubility was partially reversible and totally inhibited in the presence of galactosides, the specific ligands of PNA. Their efficacy as inhibitors of cryoinsolubility was related to their affinity for the lectin. The effects of neutral salts and particularly inhibition of the insolubility by strongly chaotropic salts indicate that charge-charge interactions are of little importance and that hydrogen bonds and/or van der Waals interactions are most probably responsible for the formation of the cryoprecipitate.

Carbohydrates↗
PubMed1981

Localization and overall structure of a mannose-rich glycopeptide from a pathologic immunoglobulin.

The structure of a mannose-rich glycopeptide from a human pathological IgM has been investigated. It belongs to the group I (simple) glycopeptides and contains only mannose and N-acetylglucosamine residues in a molar ratio of 10:2. The structures of its oligosaccharide moiety and peptide chain have been determined: its molecular localization is specified and the relation between its biosynthesis and the oligosaccharide structure determine is discussed. Based on the alpha- and beta-mannosidase digestions and permethylation studies for the oligosaccharide moiety, and on the results obtained after sequential analysis of the peptide chain, the following structure is proposed for the mannose-rich IgM Du glycopeptide: (Formula: see text). The recovery of one molecule of this glycopeptide per molecule of heavy chain and the determination of the amino acid sequence have led us to locate this glycopeptide on asparagine 402 of the Fc portion of the heavy chain mu of IgM Du.

Amino Acid Sequence↗
PubMed1981

Correlation between the regeneration of cell surface glycoproteins and the cell re-adhesion to the substratum in trypsin-treated chick fibroblasts at various stages of embryo development.

The ability of fibroblasts from 8- to 16-day-old chick embryos to adhere to a substratum was altered by trypsin treatment. The consequences of this treatment were investigated on cell re-adhesion to the substratum and cell morphology in relation to the regeneration of cell surface glycoproteins as estimated by the incorporation of [3H]leucine and [14C]glucosamine. Cell re-adhesion, cell shape and restoration of cell surface glycoproteins of the fibroblasts from chick embryos were markedly alike for each stage of embryo development. Age-dependent differences were noted. The fibroblasts from 8-day-old embryos re-adhered progressively more rapidly than fibroblasts from 16-day-old embryos. The fibroblast morphology appeared to be dependent on the re-adhesion of cells to the substratum. Parallel to the re-adhesion, the cell surface glycoprotein recovery reached at least 90% in fibroblasts from 8-day-old embryos and only about 70% in fibroblasts from 16-day-old embryos after a 4 h culture as compared to the control cultures. These percentages coincided with 73% (fibroblasts from 8-day-old embryos) and 40% (fibroblasts from 16-day-old embryos) adhesion recovery. The results are discussed in terms of a possible mechanism for cell surface recovery.

Animals↗
PubMed1980

[Comparison of the effects of concanavalin A on cell growth and the transport of 3-O-methylglucose in chick embryo fibroblasts].

The proliferative capacity of Chick embryo fibroblasts was modified by Con A treatment. Con A decreased the growth of fibroblasts from young embryos (8 days), whereas the lectin stimulated the growth of fibroblasts from older embryos (16 days). This differential effect of Con A did not result from changes in cellular permeability to thymidine, but rather from Con A induced modifications of hexose transport. Changes in hexose transport would cause, as a response, parallel modifications in glycolysis and hence energy charge, which would alter proliferative capacity.

3-O-Methylglucose↗
PubMed1980

Subunit structure of Vicia graminea anti-(blood-group N) lectin.

The subunit of the Vicia graminea lectin with blood-group-N specificity was examined by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and gel filtration in 6M-guanidinium chloride, and its molecular weights was found to be 25 000. The unique N-terminal sequence fof the first nine residues of the lectin confirmed that Vicia lectin consists of four identical chains non-covalently linked. Finally the microheterogeneity of the lectin shown by analytical isoelectric focusing is discussed.

Amino Acid Sequence↗
PubMed1980

Toxic effect of Ricinus lectin on hepatoma cells in relation to enzyme modification of the cell surface.

With regard to the toxic effects of Ricinus lectin, neuraminidase-treated hepatoma cells have been found to be the most sensitive, and untreated hepatoma cells the least. Cells treated with neuraminidase and galactose oxidase exhibited an intermediate sensitivity. At 37 degrees C, the number of Ricinus lectin molecules bound to untreated, neuraminidase-treated and neuraminidase and galactose oxidase-treated cells required to being about 30% toxicity within 2 h was 15 . 10(5), 7.5 . 10(5) and 11.5 . 10(5) molecules/cell, respectively. This difference was rather small and suggests that the additional binding sites exposed following enzyme treatment were as efficient in mediating lectin toxicity as those present before enzyme treatment. Positive cooperativity was observed during Ricinus lectin binding to enzyme-treated cells at 37 degrees C and the apparent association constant increased with the increase of binding site occupancy. The binding sites on enzyme-treated cells appeared to be homogeneous since under different physical conditions (4 degrees C) the shape of the Scatchard plot could be altered in such a way as to produce a single line of slope. In contrast to enzyme-treated cells, untreated cells did not exhibit a positive cooperative process either at 37 degrees C or at 4 degrees C. We found that the toxicity of Ricinus lectin paralleled the irreversible specific binding of lectin, suggesting that only this was able to mediate the toxic effect. Our results are discussed in terms of the possible entry into the cells of Ricinus lectin and this occurs more rapidly in enzyme-treated than in untreated cells. This difference agrees with the sequence of events proposed: (i) Binding of Ricinus lectin; (ii) Clustering of lectin binding sites; and (iii) Endocytosis.

Animals↗
PubMed1979

Changes in the sensitivity of chick fibroblasts to Ricinus lectin (RCA I) toxicity in relation to the stage of embryo development.

The toxic effect of Ricinus lectin RCA I, as estimated by the inhibition of [3H]leucine incorporation, was investigated on chick-embryo fibroblasts at different stages of development. There appeared to be a differential susceptibility of chick-embryo fibroblasts to lectin RCA I. Fibroblasts from 16-day embryos were the most sensitive to its toxic effect in terms of both concentration and time, and cells from 8-day embryos were the least sensitive. This differential sensitivity to the toxic effect of lectin RCA I was closely related to the binding of the lectin: fibroblasts from 16-day embryos had more binding sites (1.5 x 10(7)/cell) with a high affinity than did 12-day (0.45 x 10(7)/cell) or 8-day embryos (0.2 x 10(7)/cell). Studies on the specificity and the removal of bound lectin RCA I by D-galactose indicated that the lectin binding was necessary but not sufficient in itself to cause the toxic effect and that the lectin needed to enter the cells in order to be toxic. The amount of lectin RCA I needed to induce a 50-60% toxicity enters fibroblasts of 16-day embryos more rapidly than those of 12- and 8-day embryos.

Animals↗