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.

Bioconversion of Beet Molasses to Alpha-Galactosidase and Ethanol.

Abstract: Molasses are sub-products of the sugar industry, rich in sucrose and containing other sugars like raffinose, glucose, and fructose. Alpha-galactosidases (EC. 3.2.1.22) catalyze the hydrolysis of alpha-(1,6) bonds of galactose residues in galacto-oligosaccharides (melibiose, raffinose, and stachyose) and complex galactomannans. Alpha-galactosidases have important applications, mainly in the food industry but also in the pharmaceutical and bioenergy sectors. However, the cost of the enzyme limits the profitability of most of these applications. The use of cheap sub-products, such as molasses, as substrates for production of alpha-galactosidases, reduces the cost of the enzymes and contributes to the circular economy. Alpha-galactosidase is a specially indicated bioproduct since, at the same time, it allows to use the raffinose present in molasses. This work describes the development of a two-step system for the valuation of beet molasses, based on their use as substrate for alpha-galactosidase and bioethanol production by Saccharomyces cerevisiae. Since this yeast secretes high amounts of invertase, to avoid congest the secretory route and to facilitate alpha-galactosidase purification from the culture medium, a mutant in the SUC2 gene (encoding invertase) was constructed. After a statistical optimization of culture conditions, this mutant yielded a very high rate of molasses bioconversion to alpha-galactosidase. In the second step, the SUC2 wild type yeast strain fermented the remaining sucrose to ethanol. A procedure to recycle the yeast biomass, by using it as nitrogen source to supplement molasses, was also developed.

Serological studies on brewing yeasts

Abstract: In a serological investigation of twelve strains of Saccharomyces carlsbergensis, three strains were found to be antigenically different from the other nine, but no physiological or morphological properties characterized either type. S. rouxii, although antigenically very similar to S. carlsbergensis, was found to be sufficiently different to allow serological differentiation. A preparation is described of a serum which agglutinates three of the twelve S. carlsbergensis strains tested, but not organisms of ten other Saccharomyces spp., including S. cerevisiae, S. ellipsoideus, S. diastaticus and S. rouxii. S. ellipsoideus, S. diastaticus and the remaining strains of S. carlsbergensis were found to be serologically identical and could only be distinguished by fermentation of melibiose and starch.

Inhibition of the adhesion of Entamoeba histolytica trophozoites to human erythrocytes by carbohydrates.

Abstract: We have analyzed the effect of 14 carbohydrates (seven monosaccharides, four disaccharides and three aminosugars) on the adhesion of Entamoeba histolytica HK9 trophozoites to human red blood cells (RBC). Amebal adhesion was significantly inhibited by five of these carbohydrates with the following order of potency: lactose (Lac) greater than N-acetylgalactosamine (GalNac) greater than melibiose (Mel) greater than galactose (Gal) greater than N-acetylglucosamine (GlcNAc). The mean inhibitory concentration of Lac was 2.66 mM. Adhesion increased by 20% in the presence of 5.5 mM glucose (Glc). Inhibition of the adhesion was lower in the absence rather than in the presence of Glc only with Gal-NAc, whereas it was similar with Lac, Mel, Gal, and GlcNAc in both cases. The initial rate of amebal adhesion decreased 27% by RBC fixation, but adhesion to fixed RBC was also inhibited by the same five carbohydrates. Inhibition was higher in mixtures containing Lac, GalNAc, and Mel, than with the same isolated carbohydrates; Lac + Gal-NAc was the most potent mixture. Inhibition decreased when Lac, GalNAc, and Mel were mixed either with Gal or GlcNAc. We conclude that E. histolytica adhesion depends on amebal metabolic energy generated from Glc and on several surface components of RBC, some of which are inactivated with glutaraldehyde whereas others are inhibited by sugars containing Gal, GlcNAc, or Gal-NAc residues.

Protective, anti-tumor monoclonal antibody recognizes a conformational epitope similar to melibiose at the surface of invasive murine melanoma cells.

Abstract: Polyclonal and monoclonal antibodies (MAbs) have been raised against B16F10 cells collected from growing tumors in vivo or grown in culture media supplemented with normal mouse serum to avoid xenogeneic reactivity. Antibody binding to glutaraldehyde-fixed melanoma cells and Melan A melanocytes was assayed using chemiluminescent-enzyme-linked immunosorbent assay (CL-ELISA) for increased sensitivity. Most of the reactivity of antitumor polyclonal IgG (92%) was inhibitable by a carbohydrate pool consisting of melibiose, mannose, lactose, and sialic acid. Two monoclonal IgG(2a) antibodies, A4 and B11, had their reactivity to melanoma cells completely and specifically inhibited by melibiose. MAb A4 did not bind to alpha-galactosyl residues abundantly expressed in a protozoan mucin used as substrate, and its binding to the tumor cells was not affected by alpha-galactosidase treatment or addition of alpha-methyl-galactopyranoside or raffinose. Recognition of a mimotope similar to melibiose is suggested. MAb is cytotoxic in vitro in a complement-mediated reaction and effectively neutralizes melanoma cells protecting syngeneic mice against tumor development in vivo. This MAb is thus an important tool for further studies on antitumor adjuvant therapy combined with other agents associated with immuno- and chemotherapy of invasive melanoma.