Search results for "Arid"

Solid-Phase Synthesis of a Sialyl-Tn-Glycoundecapeptide of the MUC1 Repeating Unit

1997

The synthesis of glycopeptides carrying tumour-associated antigens is of interest for cancer diagnosis and treatment. Here, a very efficient route lo disaccharide threonine building block 8 is presented which allows the introduction of the sialyl-Tn antigen into a peptide. The syntheses of the undecapeptide and the sialyl-Tn-containing glycoundecapeptide, which are a part of the repeating unit of MUC1, were performed by solid-phase synthesis with an allylic anchor cleavable under neutral conditions. After detachment from the resin, the peptide and the glycopeptide arc completely deprotected giving the target compounds 13 and 15, respectively.

Lentils enhance probiotic growth in yogurt and provide added benefit of antioxidant protection

2013

Abstract We evaluated the antioxidant potential of lentil polysaccharides in stimulating the growth of probiotic bacteria in yogurt. Microbial counts, pH and total titratable acidity (TTA) were measured in yogurt samples containing starter cultures with or without probiotic bacteria, supplemented with whole ground green lentils. Additionally, the antioxidant potential of polysaccharides extracted from green, red, and dehulled red lentils were measured by oxygen radical absorbance capacity (ORAC) assay. Results demonstrate that green lentils selectively enhanced the number of probiotic bacteria in yogurt in the initial stages of storage and maintained overall microbial counts (starter cultur…

α-L-rhamnosidases: Old and New Insights

2007

L-Rhamnose is a component of plant cell wall pectic polysaccharides (Mutter et al., 1994; Ridley et al., 2001), glycoproteins (Haruko and Haruko, 1999) and secondary metabolites such as anthocyanins (Renault et al., 1997), flavonoids (Bar-Peled et al., 1991) and triterpenoids (Friedman and McDonald, 1997). It has also been found in bacterial heteropolysaccharides (Hashimoto and Murata, 1998), rhamnolipids (Ochsner et al., 1994) and in the repeating units of the O-antigen structure of the lipopolysaccharide component of bacterial outer membranes (Chua et al., 1999). Some rhamnosides are important bioactive compounds, e.g. cytotoxic saponins (Bader et al., 1998; Yu et al., 2002), antifungal p…

Influence of some physicochemical factors on the viscosity of aqueous levan solutions ofZymomonas mobilis

1998

Zymomonas mobilis strain 113 “S” produces levan – an extracellular, viscous, biologically active, non-toxic fructose polymer with a unique structure and extraordinary properties. This polysaccharide was isolated at two different degrees of purity by alcohol precipitation from aqueous solutions and was characterized with respect to some rheological properties and stability of viscous solutions. The effects of temperature, pH and salt concentration on the viscosity of 1–3% levan solutions were examined. The viscosity of levan solutions was found to be quite stable and reversible at room temperature over a wide range of pH from 4 to 11. The viscosity was slightly affected by increased salt con…

Alkaline Pre-treatment of Hardwood Chips Prior to Delignification

2013

Scots pine (Pinus sylvestris) chips were pre-treated with alkaline solutions (alkali charges of 1, 2, 3, 4, 6, and 8% of NaOH on the oven-dried wood material) at 130°C and 150°C for various treatment times (30, 60, 90, and 120 minutes). Under these conditions, 2.0–13.6% of the wood d.s. was dissolved into the aqueous hydrolysates. The soluble organic fraction was primarily characterized in terms of carbohydrates (monosaccharides and oligo-/polysaccharides) and their alkali-catalyzed degradation products: aliphatic carboxylic acids containing, besides non-volatile hydroxy carboxylic acids, volatile formic and acetic acids. With increasing alkali charge, temperature, and time, the enhanced fo…

1994

The synthesis of linear carbohydrate modified polysiloxanes has been successfully performed by hydrosilation of functionalized and protected carbohydrate derivates. The functionalization (allyl glycosilation) may be applied to a wide variety of reducing carbohydrates. In this study, mono-, di- and oligosaccharides were converted by a simple two-step reaction (β-acetylation and allyl glycosilation) into active compounds, allowing the polymer analogous addition to random poly[dimethyl-co-hydromethyl]siloxanes (hydrosilation). By variation of the Si–H amount in the starting polymers, polysiloxanes with 1.5% to 56% (by weight) carbohydrate content were prepared. At small degrees of substitution…

Water-soluble polysaccharides from Opuntia stricta Haw. fruit peels: Recovery, identification and evaluation of their antioxidant activities

2015

Abstract Opuntia stricta Haw. is considered as one of the most common cactus plant growing in Tunisia. Extracting valuable compounds from its fruit peel, considered as by-product, is drawing more and more attention, making it on the verge of commercialization. Water-soluble polysaccharides were extracted from Opuntia stricta Haw. peels, and their chemical composition assessed using thin layer chromatography. The antioxidant activities of the extracted polysaccharides were assessed using 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity, total antioxidant activity and reducing power capacity. The extraction yield of water-soluble polysaccharides was 7.53±0.86%. The chemical comp…

Effect of chelatants on gellan gel rheological properties and setting temperature for immobilization of living bifidobacteria.

1993

The effect of various concentrations of sequestrants (sodium citrate, sodium metaphosphate, and EDTA) was studied on gellan gel (1.5-2.5% (w/v)) setting temperature and rheological properties. Addition of EDTA between 0 and 0.8% (w/v) led to a progressive decrease of setting temperature. Citrate and metaphosphate decreased this parameter when added up to 0.4 or 0.6%, depending on gellan gum concentration, eventually resulting in the absence of gel formation at room temperature for the 1.5% gellan solution containing 0.4% citrate. This effect was accompanied by a significant decrease of gel strength and stiffness and might be attributed to the binding of the divalent cations required for cha…

Patterns of wall synthesis inSaccharomyces cerevisiae

1979

Wall formation inSaccharomyces cerevisiae seems to be the result of two main patterns of wall material deposition: (i) around the whole periphery of the cell in nonbudding ones, and (ii) mainly at the tip of the daughter cell or at the cross wall that separates dividing cells. This interpretation has been obtained following experiments in which RNA or protein synthesis has been inhibited. Under these conditions, glucan formation takes place, and wall thickening is probably due to the accumulation of this polysaccharide. Furthermore, once a pattern of wall deposition has been established, it is not modified by inhibition of RNA or protein synthesis.

Relationships Between Dimorphism, Cell Wall Structure, and Surface Activities in Candida albicans

1991

Most cells are covered with a complex network of interacting molecules that form the extracellular matrix. These molecules (proteins and polysaccharides) are secreted locally and interact among themselves to form an organized structure outside the cell plasma membrane. In unicellular eukaryotic organisms and plant cells, this structure is reinforced to withstand osmotic changes in the external environment, giving rise to the so-called cell wall.