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Biomedical subjects

M Basu

Publications and source records attributed to M Basu.

At least 91 records · Page 5Linked to original sources
PubMed1982

Biosynthesis in vitro of sialyl(alpha 2-3)neolactotetraosylceramide by a sialyltransferase from embryonic chicken brain.

A sialyltransferase activity present in 7- to 12-day-old embryonic chicken brain catalyzes the transfer of sialic acid from CMP-sialic acid to the terminal galactose residue of [3H]nLcOse4Cer ([3H]Gal(beta 1-4).GlcNAc(beta 1-3)Gal(beta 1-4)Glc-Cer) to form NeuAc(alpha 2-3)-[3H]nLcOse4Cer (LM1 ganglioside). The product is sialidase-labile (96%), and the NeuAc group is linked to O-3 of the terminal galactose residue. The (alpha 2-3) linkage between sialic acid and the terminal galactose was determined on the basis of identification of 2,4,6-tri-O-methyl[3H]galactose obtained after hydrolysis of the permethylated enzymatic product. The CMP-sialic acid:nLcOse4Cer (alpha 2-3)sialyltransferase activity sediments (90%) at the junction of 1.2 M and 1.5 M on a discontinuous sucrose density gradient when still membrane bound (insoluble in 0.2% Triton X-100). The enzyme preparation also catalyzes the transfer of sialic acid from CMP-sialic acid to O-3 of GgOse4Cer (Gal(beta 1-3)GalNAc(beta 1-4)Gal(beta 1-4)Glc-Cer) to form NeuAc (alpha 2-3)GgOse4Cer (GM1b). Substrate inhibition studies indicate that these two reactions are probably catalyzed by the same enzyme.

Animals↗
PubMed1982

Biosynthesis in vitro of a blood group B-active fucose-containing hexaglycosylceramide from neolactopentaosylceramide in bovine spleen.

A solubilized alpha-fucosyltransferase activity has been isolated from a bovine spleen Golgi-rich membrane fraction. The enzyme transfers fucose from GDP-beta-L-fucose to a blood group B-active pentaglycosylceramide acceptor (Gal(alpha 1-3)Gal(beta 1-4)GlcNAc(beta 1-3)Gal(beta 1-4)Glc-ceramide) isolated from rabbit erythrocytes. Treatment of the membranes with 0.2% (final concentration) sodium taurodeoxycholate detergent produced maximal recovery (90%) of activity. A cationic detergent, G-3634-A, is required for optimal activity and the enzyme does not require addition of exogenous metal ion for activation. The purified 14C-labeled product of the reaction migrated with human blood group B-active hexaglycosylceramide on Silica Gel G thin layer plates. After treatment with fig alpha-galactosidase, the radioactive pentaglycosylceramide migrated with human H-active glycosphingolipid. The 14C-labeled product inhibited the hemagglutination reaction of B-type erythrocytes with Bandeiraea simplicifolia lectin and anti-B serum and formed a precipitin line with Euonymus europeus lectin. Treatment of the 14C-labeled product with alpha-fucosidase (Venus mercenaria) or weak acid at 100 degrees C for 2 h released 80-90% of the bound radioactive fucose.

ABO Blood-Group System↗
PubMed1982

Studies on superoxide dismutase activities in virulent and avirulent strains of Agrobacterium tumefaciens and also in normal and crown gall tumor cells of Bryophyllum calycinum.

Superoxide dismutase activity in virulent strains of Agrobacterium tumefaciens was found to be higher than that in avirulent strains. Polyacrylamide gel electrophoresis revealed two isoenzymes in both these strains. These isoenzymes are suggested to be iron and manganese containing superoxide dismutases. Crown gall tumor cells of the plant Bryophyllum calycinum were found to have higher superoxide dismutase activity than the normal plant cells. Polyacrylamide gel electrophoresis revealed two isoenzymes in both normal and crown gall tumor cells. Advantages of the higher superoxide dismutase activities in respect of the survival of virulent strains of A. tumefaciens and crown gall tumor growth have been discussed.

Iron↗
PubMed1979

Differential activities of glycolipid glycosyltransferases in Tay-Sachs disease: studies in cultured cells from cerebrum.

Four different glycolipid:glycosyltransferase activities involved in the biosynthesis in vitro of gangliosides and blood group-related glycosphingolipids have been tested in a simian virus 40-transformed glial cell culture derived from the cerebrum of a fetus with Tay-Sachs disease (TSD). The TSD cultured brain cells contained little activity of either UDP-Gal:GM2(beta 1-3)galactosyltransferase (GalT-3; EC 2.4.1.62), which catalyzes the formation of GM1a from GM2 (tay-Sachs) ganglioside, or GDP-Fuc:nLcOse4Cer (alpha 1-2)fucosyltransferase (FucT-2; EC 2.4.1.89), which catalyzes the formation of H1 glycolipid from nLcOse4Cer. These cells contained a potent inhibitor of the second reaction (catalyzed by a Golgi-rich membrane fraction from bovine spleen), whereas no inhibition of the first reaction (catalyzed by a membrane fraction from 14-day-old embryonic chicken brain) was observed. The activity of UDP-Gal:LcOse3Cer(beta 1-4)galactosyltransferase (GalT-4; EC 2.4.1.86) was 30- to 80-fold higher than the activity of GalT-3. The presence of CMP-AcNeu:nLcOse4Cer sialyltransferase activity and the absence of either GalT-3 or FucT-2 suggested a probable pathway for the synthesis of sialylneolactotetraosylceramide [GM1b(GlcNAc)] in addition to a specific blockage of GM1a ganglioside synthesis from GM2 in these TSD transformed cells.

ABO Blood-Group System↗
PubMed1978

Biosynthesis in vitro of fucose-containing glycosphingolipids in human neuroblastoma IMR-32 cells.

Two different glycolipid:fucosyltransferase activities involved in the biosynthesis in vitro of blood group-related glycosphingolipids have been detected in a membrane preparation isolated from a human neuroblastoma-derived clonal cell line, IMR-32. The membrane preparation contains an alpha (1,2)-fucosyltransferase (EC 2.4.1.89) that catalyzed the transfer of vucose from GDP--[14C]fucose to neolactotetraosylceramide or neolactopentaosylceramide to form types H-I and B-I glycolipids, respectively. The second fucosyltransferase catalyzes the transfer of fucose to lactotriaosylceramide [GlcNAc(beta1-3)Gal(beta1-4)Glc-Cer] to form a tetraglycosylceramide intermediate of the novel Lea-type glycolipid. UDP-galactose:lactotriaosylceramide beta-galactosyltransferase (EC 2.4.1.86) had 4 times the activity of UDP-galactose:alpha-galactosyltransferase (EC 2.4.1.87) when tested under similar conditions. alpha-Fucosyltransferase activities and the incorporation of [14C]fucose into glycoproteins and glycolipids were also compared in cells differentiated in the presence of 4 micron BrdUrd and 6-mercaptoguanosine.

ABO Blood-Group System↗
PubMed1975

Enzymatic synthesis of a blood group H-related glycosphingolipid by an alpha-fucosyltransferase from bovine spleen.

An alpha-fucosyltransferase activity has been detected in a purified membrane preparation isolated from bovine spleen which catalyzes the transfer of L-fucose from GDP-L-[14C]-fucose to a tetraglycosylceramide (Lac-nTet-cer, Galbetal-4GlcNAcbeta1-3Galbeta1-4-Glc-cer) to form the blood group H-related glycosphingolipid. The membrane preparation contained a highly active endogenous nonlipid acceptor, which could be precipitated by 5% trichloroacetic acid or chloroform-methanol-water (6:3:5, v/v/v), whereas there was little endogenous glycosphingolipid acceptor. The optimum pH value for the incorporation of L-fucose was 6.4 in cacodylate-HCl buffer. The Km values were 0.6 mM and 0.36 mM for Lac-nTet-cer and GDP-L-fucose, respectively. The 14C-labeled product of the reaction was isolated and purified; it migrated with human erythrocyte blood group H-active pentaglycosylceramide. the terminal [14C]fucose was hydrolyzed 85% and 55% by 0.1 N trichloroacetic acid at 100 degrees for 2 hours and Charonia lampas alpha-fucosidase (19 hours at 37 degrees), respectively. The 14C-labeled product inhibited the hemagglutination reaction of O-type cells against eel anti H(O) globulin and formed a precipitin line with Ulex europeus lectin.

Animals↗