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.

The potential of lactulose and melibiose, two novel trehalase-indigestible and autophagy-inducing disaccharides, for polyQ-mediated neurodegenerative disease treatment

Abstract: The unique property of trehalose encourages its pharmaceutical application in aggregation-mediated neurodegenerative disorders, including Alzheimer's, Parkinson's, and many polyglutamine (polyQ)-mediated diseases. However, trehalose is digested into glucose by trehalase and which reduced its efficacy in the disease target tissues. Therefore, searching trehalase-indigestible analogs of trehalose is a potential strategy to enhance therapeutic effect. In this study, two trehalase-indigestible trehalose analogs, lactulose and melibiose, were selected through compound topology and functional group analyses. Hydrogen-bonding network analyses suggest that the elimination of the hydrogen bond between the linker ether and aspartate 321 (D321) of human trehalase is the key for lactulose and melibiose to avoid the hydrolyzation. Using polyQ-mediated spinocerebellar ataxia type 17 (SCA17) cell and slice cultures, we found the aggregation was significantly prohibited by trehalose, lactulose, and melibiose, which may through up-regulating of autophagy. These findings suggest the therapeutic applications of trehalase-indigestible trehalose analogs in aggregation-associated neurodegenerative diseases.

Characterization of α-galacto-oligosaccharides formed via heterologous expression of α-galactosidases from Lactobacillus reuteri in Lactococcus lactis

Abstract: α-Galacto-oligosaccharides (α-GOS) are produced by transgalactosylation reactions of α-galactosidase (α-Gal) or by conversion of raffinose family oligosaccharides by levansucrase Similarly to β-GOS, α-GOS have the potential to mimic glycan receptors on eukaryotic cells and act as molecular decoys to prevent bacterial infection; however, data on transgalactosylation reactions of α-Gal remain scarce The α-Gal gene sequence from Lactobacillus reuteri was cloned into an α-Gal negative strain of Lactococcus lactis Transgalactosylation reactions were achieved using crude cell extracts with melibiose or raffinose as galactosyl donor and fucose, N-acetylglucosamine or lactose as galactosyl acceptor The composition, sequence and most linkage types of α-GOS formed with acceptors saccharides were determined by liquid chromatography-tandem mass spectrometry α-Gal of Lactobacillus reuteri formed (1 → 3)-, (1 → 4)- or (1 → 6)-linked α-GOS but exhibited a preference for formation of (1 → 6)-linkages Fucose, N-acetylglucosamine and lactose were suitable galactosyl acceptors for α-Gal of L reuteri, resulting in formation of (1 → 3)-, (1 → 4)- or (1 → 6)-linked hetero-oligosaccharides By determining the structural specificity of α-Gal and increasing the variation of oligosaccharides produced by introducing alternative acceptor sugars, this work supports further studies to assess α-GOS pathogen adhesion prevention in mammalian hosts

Stachyose synthesis in mature leaves of Cucumis melo. Purification and characterization of stachyose synthase (EC 2.4.1.67)

Abstract: Galactinol: raffinose-6-galactosyltransferase (EC 2.4.1.67), a stachyose synthase, was extracted from mature leaves of Cucumis melo cv. Ranjadew and was purified to homogeneity by (NH4)2SO4 precipitation, ion-exchange chromatography, gel-filtration and non-denaturing polyacrylamide gel electrophoresis. A specific activity of 516 μkat · mg-1 and a 160-fold purification was achieved. The pH optimum of the enzyme reaction was found to be 6.8 in sodium-phosphate buffer, and the temperature optimum 32° C. The purified enzyme was very sensitive towards SH-poisons but its reaction was hardly affected by changes in the ion composition of the assay medium. The two-substrate enzyme was specific for galactinol and raffmose; uridine-diphosphate galactose and p-nitrophenyl-α-d-galactoside as well as melibiose were not accepted by the purified enzyme. Stachyose synthesis was competitively inhibited by concentrations >4 mM raffinose as well as 2.5 mM galactinol. The Km values determined under non-saturating conditions were 3.3 mM for raffinose and 7.7 mM for galactinol. Myoinositol was a strong competitive inhibitor with a Ki of 1.8mM. Galactinol was hydrolyzed in the absence of raffinose with a Km of 0.8 mM. The pure enzyme is a protein with a molecular weight of at least 95 kDa and an isoelectric point of 5.1. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed the presence of two subunits of 45 and 50 kDa. Polyclonal antibodies from rabbit were obtained which were specific for the native enzyme but cross-reacted with other proteins separated under denaturing conditions.

Characterization of genetically transformed Saccharomyces cerevisiae baker's yeasts able to metabolize melibiose

Abstract: Three transformant (Mel+) Saccharomyces cerevisiae baker's yeast strains, CT-Mel, VS-Mel, and DADI-Mel, have been characterized. The strains, which originally lacked alpha-galactosidase activity (Mel-), had been transformed with a DNA fragment which possessed an ILV1-SMR1 allele of the ILV2 gene and a MEL1 gene. The three transformed strains showed growth rates similar to those of the untransformed controls in both minimal and semi-industrial (molasses) media. The alpha-galactosidase specific activity of strain CT-Mel was twice that of VS-Mel and DADI-Mel. The yield, YX/S (milligrams of protein per milligram of substrate), in minimal medium with raffinose as the carbon source was 2.5 times higher in the transformed strains than in the controls and was 1.5 times higher in CT-Mel than in VS-Mel and DADI-Mel. When molasses was used, YX/S (milligrams of protein per milliliter of culture) increased 8% when the transformed strains CT-Mel and DADI-Mel were used instead of the controls. Whereas no viable spores were recovered from either DADI-Mel or VS-Mel tetrads, genetic analysis carried out with CT-Mel indicated that the MEL1 gene has been integrated in two of three homologous loci. Analysis of the DNA content by flow cytometry indicated that strain CT-Mel was 3n, whereas VS-Mel was 2n and DADI-Mel was 1.5n. Electrophoretic karyotype and Southern blot analyses of the transformed strains showed that the MEL1 gene has been integrated in the same chromosomic band, probably chromosome XIII, in the three strains.(ABSTRACT TRUNCATED AT 250 WORDS)