Topic
Melibiose
About: Melibiose is a research topic. Over the lifetime, 1002 publications have been published within this topic receiving 27300 citations. The topic is also known as: Melibiose.
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TL;DR: The results raise the possibility that nonreducing terminal α-D-galactosyl-containing glycoproteins composed of heterogeneous carbohydrate chains may be present on the surface of a number of different murine tumor cells as well as on human type B erythrocytes.
Abstract: A novel 36kDa rhamnose-binding lectin isolated from Plecoglossus altivelis roe (PA 36), a probe for L-rhamnose and α-D-galactosyl nonreducing termini, bound to and agglutinated murine tumor cells rather than human type B erythrocytes. PA 36 was purified by DEAE-cellulose ion exchange and rhamnose-Sepharose affinity chromatography. The most effective saccharide in the agglutination inhibition assay was L-rhamnose. The α-D-galactosyl containing saccharides, such as melibiose, raffinose and stachyose, were more effective than the β-D-galactosyl containing saccharide, lactose. Lectin binding glycoproteins were determined by SDS-PAGE and blotting, followed by reaction with horseradish peroxidase-labeled PA 36. The glycoproteins ranging in molecular weight from 66, 000 to 72, 000 and deriving from murine tumor cells and bands 4.1 and 4.2 deriving from human type B erythrocytes were PA 36-binding glycoproteins. These results raise the possibility that nonreducing terminal α-D-galactosyl-containing glycoproteins composed of heterogeneous carbohydrate chains may be present on the surface of a number of different murine tumor cells as well as on human type B erythrocytes.
3 citations
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TL;DR: In (NH4)2-SO4-precipitated membrane preparations, maltose binds more strongly than other disaccharides and competes mutually for uptake with D-glucose and Phloretin inhibits the binding of glucose much more than that of maltose.
Abstract: Disaccharides (sucrose, lactose, melibiose, cellobiose, trehalose, maltose, and isomaltose) are not transported across the human erythrocyte membrane. Maltose alone is bound in appreciable amounts to the intact cell as well as ghost membranes and competes mutually for uptake with D-glucose. In (NH4)2SO4-precipitated membrane preparations, maltose binds more strongly than other disaccharides (KD = 1.3 × 10−5 M; maximum binding capacity, 71 pmol/mg protein) and again competes mutually with D-glucose. Phloretin inhibits the binding of glucose much more than that of maltose.
3 citations
01 Jan 1988
TL;DR: A vector constructed to evaluate terminator or attenuator of transcription quantitatively is a plasmid possessing lac promoter-polylinker-CAT(chloramphenicol acetyltransferase) gene, and it is found that a DNA fragment containing a large stem-loop structure with boxA sequence in it caused strong reduction of gene expression.
Abstract: We constructed a vector to evaluate terminator or attenuator of transcription quantitatively. This vector is a plasmid possessing lac promoter-polylinker-CAT(chloramphenicol acetyltransferase) gene. DNA fragment of interest can be inserted into the polylinker site, and the effect of the DNA fragment on the expression of the downstream gene is evaluated from the CAT activity. We analyzed gene expression of the melibiose operon of Escherichia coli using this plasmid, and found that a DNA fragment containing a large stem-loop structure with boxA sequence in it, which was present between melA and melB, caused strong reduction of gene expression. This DNA portion seems to be responsible for reduced expression of melB, the second gene of the melibiose operon.
3 citations
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TL;DR: The production ratio of alpha-galactosidase and melibiose permease is regulated at two levels: 1) transcription and 2) mRNA stability.
Abstract: The organization of the melibiose operon of Escherichia coli is promoter-melA-melB. The amount of the product (alpha-galactosidase) of the first gene (melA) is much larger than that of the product (melibiose permease) of the second gene (melB). Using the chloramphenicol acetyltransferase gene (cat) as reporter, we found that there was an element between melA and melB, which reduced the expression of the downstream gene, melB. This region contained a boxA-like sequence, which is known as a binding site for an attenuation factor, NusA. Northern hybridization analysis revealed that the ratio of melA mRNA and melAB mRNA was comparable with the ratio of the melA and melB products. We also found that the melA mRNA was about 3-fold more stable than the melAB mRNA. Experimental results obtained with a nusAts mutant suggested that the NusA protein is involved in the reduced expression of the melB gene. We conclude that the production ratio of alpha-galactosidase and melibiose permease is regulated at two levels: 1) transcription and 2) mRNA stability.
3 citations
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11 Apr 2014TL;DR: In this article, a trans-sialidated mono-and oligo-saccharides, produced with the mutant enzyme, are useful in preparing infant formula, a prebiotic nutritional supplement, and a food supplement.
Abstract: The invention provides a mutant enzyme having trans-sialidase activity (EC 3.2.1.18), characterized by an enhanced trans-sialidase:sialidase ratio when compared to its parent sialidase enzyme. Further the enzyme may be used in a method for trans-sialylating mono- and oligo-saccharides, including galacto-oligosaccharides (GOS), fructo-oligosaccharides (FOS), malto-oligosaccharides (MOS), isomalto-oligosaccarides (IMO), lactulose, melibiose, maltose, glycosyl sucrose, lactosucrose and fucose. Trans-sialidated mono- and oligo-saccharides, produced with the mutant enzyme, are useful in preparing infant formula, a prebiotic nutritional supplement, and a food supplement.
3 citations