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R Cacan

Publications and source records attributed to R Cacan.

64 records · Page 4Linked to original sources
PubMed1978

Occurrence of two fucosyltransferase activities at the outer surface of rat lymphocytes.

To demonstrate the existence of ectofucosyltransferase activities on the outer surface of rat lymphocytes, we measured fucosyltransferase activities on whole cells using procedures enabling us to exclude the possibility of misleading results due to precursor hydrolysis and intracellular utilization of the free fucose, and to take into account the contamination by intracellular enzymes freed by the small percentage of broken cells. The described ectofucosyltransferases are able to catalyze the transfer of fucosyl residues from GDP-fucose to the endogenous membrane acceptors but the transfer activity towards exogenous acceptors is restricted to low molecular weight compounds. Use of galactose and di-N-acetylchitobiose as exogenous acceptors and concomitant study of the specific inhibition by N-ethylmaleimide enabled us to detect both types of ectofucosyltransferases: a GDP-fucose: galactoside ectofucosyltransferase and a GDP-fucose: N-acetylglucosaminide ectofucosyltransferase.

Animals↗
PubMed1977

Effect of cyclic nucleotides in vitro assays of rat liver galactosyltransferase.

Experiments with rat liver microsomal galactosyltransferase has been developed to test the effect of cyclic nucleotides on the transfer activity. An overall stimulation is observed when cAMP or cGMP (concentration higher that 10(-6) M) are added to the incubation medium. However, more detailed experiments show that the cyclic nucleotides do not act as direct effectors of the enzyme but present the precursors degradation by the glycosylnucleotide pyrophosphatases.

Animals↗
PubMed1976

Ectogalactosyltransferase. Presence of enzyme and acceptors on the rat lymphocyte cell surface.

Experiments are described to demonstrate the existence of ectogalactosyltransferase activity on the lymphocyte surface. The procedures described enable us to exclude the possibility of misleading results due to precursor hydrolysis and intracellular utilization of the free galactose. This depicted transferase is able to catalyse the transfer of a galactosyl residue from UDP-galactose to a nonphagocytosable exogenous acceptor and to endogenous membrane acceptors. The cells galactosylated in this way acquired new agglutinating properties with soybean agglutinin, which proves the external position of the galactosyl residues incorporated on the cell surface.

Animals↗
PubMed1975

Labeling of soybean agglutinin by oxidation with sodium periodate followed by reduction with sodium [3-H]borohydride.

Periodate oxidation of soybean agglutinin, a glycoprotein lectin, resulted in destruction of up to 5 out of the 9 mannose residues present in each of its subunits (MW 30,000) without any loss of hemagglutinating activity. The oxidation did, however, abolish the interaction of soybean agglutinin with concanvalin A, as measured by quantitative precipitation. Reduction with sodium [3-H]borohydride of soybean agglutinin in which 4 out of 9 mannose residues per subunit were oxidized, afforded a radioactive product which retained full hemagglutinating activity and was indistinguishable from the native lectin by gel filtration, gel electrophoresis, and affinity chromatography. These results establish that the integrity of the carbohydrate side chain of soybean agglutinin is not essential for the biological activity of the lectin, and suggest a general method for the preparation of radioactive glycoprotein lectins.

Borohydrides↗