Number Of Disaccharides Research Articles

Optical Clearing of Biological Tissues with a Number of Disaccharides

Optical Clearing of Biological Tissues with a Number of Disaccharides

Characterisation of two unique unifloral honeys from the boreal coniferous zone: lingonberry and mire honeys

Studies of unifloral honeys are rare in Finland, and thus there are no common traits accepted for their characterization. In our study lingonberry and mire were characterized. The physico-chemical, organoleptic and melissopalynological properties and phenolic composition of the honeys were analysed and the floral origin of the mire honey was considered. Lingonberry honey is reddish and has a flavour of toffee, whereas mire honey has very strong aroma and reddish colour. Both honeys have high electrical conductivity and pH when compared to Finnish polyfloral honeys. They are both rich in fructose, while the number of disaccharides in lingonberry honey is four and in mire honey six. Lingonberry honey has three unifloral specific phenolic compounds. Mire honey has no unifloral-specific phenolic compounds, and its floral origin is not clearly defined.

Two Gr Genes Underlie Sugar Reception in Drosophila

We have analyzed the molecular basis of sugar reception in Drosophila. We define the response spectrum, concentration dependence, and temporal dynamics of sugar-sensing neurons. Using in situ hybridization and reporter gene expression, we identify members of the Gr5a-related taste receptor subfamily that are coexpressed in sugar neurons. Neurons expressing reporters of different Gr5a-related genes send overlapping but distinct projections to the brain and thoracic ganglia. Genetic analysis of receptor genes shows that Gr5a is required for response to one subset of sugars and Gr64a for response to a complementary subset. A Gr5a;Gr64a double mutant shows no physiological or behavioral responses to any tested sugar. The simplest interpretation of our results is that Gr5a and Gr64a are each capable of functioning independently of each other within individual sugar neurons and that they are the primary receptors used in the labellum to detect sugars.

1H NMR chemical shifts of hydroxy protons in conformational analysis of disaccharides in aqueous solution

In a continuing study on the use of hydroxy protons in conformational analysis of saccharides in aqueous solution by NMR spectroscopy, a number of disaccharides with 1,3-, 1,4- and 1,6-linkages have been investigated. The 1H-NMR chemical shifts, vicinal coupling constants (3JCH,OH), temperature coefficients and rates of exchange with the solvent have been measured for the hydroxy protons. Most of the hydroxy proton signals in the disaccharides have chemical shifts similar (|Δδ| ≤ 0.3 ppm) to those in the corresponding methyl monosaccharides. Three hydroxy protons, however, O(2)H in β-L-Fucp-(1→3)-α-D-Glcp-OMe, O(3)H in β-L-Fucp-(1→4)-α-D-Galp-OMe and O(6)H in β-L-Fucp-(1→4)-α-D-Glcp-OMe show a large upfield shift (Δδ ≤ −0.3 ppm) attributed to the proximity of the hydroxy proton to the ring oxygen of the neighbouring sugar. In β-L-Fucp-(1→4)-α-D-Galp-OMe, the chemical shift, 3JCH,OH and temperature coefficient of the O(3)H signal indicate that a weak hydrogen bond interaction exists between O(3)H and O(5′). In β-L-Fucp-(1→4)-α-D-Glcp-OMe, the chemical shift and the NOEs involving the O(6)H signal suggest a preference for the trans-gauche conformation around the C5–C6 bond.

Coupling of Glycal Derived Thioethyl Glycosyl Donors with Glycal Acceptors. An Advance in the Scope of the Glycal Assembly

Glycals were converted into thioethyl glycosyl donors through 1,2-anhydrosugar intermediates. Various participating groups in the C-2 position were examined for formation of β-glucosyl, β-galactosyl, and α-mannosyl linkages. A number of disaccharides was prepared employing a novel coupling protocol involving thioethyl 2-pivaloyl glycosyl donors and glycal acceptors. Using this methodology, a linear tetrasaccharide containing exclusively β-glucosyl-(1→4) linkages was prepared in high yields. Ready application to α-mannosylation and C2 branching are other hallmarks of the method.

Enzyme stabilization be ectoine-type compatible solutes: protection against heating, freezing and drying

The aim of this study was to elucidate the protective effect of the new compatible solutes, ectoine and hydroxyectoine, on two sensitive enzymes (lactic dehydrogenase, phosphofructokinase). The solutes tested also included (for reasons of comparison) other compatible solutes such as glycine betaine and a number of disaccharides (sucrose, trehalose, maltose). All compatible solutes under investigation displayed remarkable stabilizing capabilities. However, the degree of protection depended on both the type of solute chosen and the enzyme used as a test system. The most prominent protectants were trehalose, ectoine and hydroxyectoine, which are very often found in nature (singly or in combinationn) as part of the compatible solute “cocktail” of moderately halophilic eubacteria.

THE ISOLATION OF OLIGOSACCHARIDES FROM THE CELL-WALL POLYSACCHARIDE OF LACTOBACILLUS CASEI, SEROLOGICAL GROUP C

1. A number of disaccharides and oligosaccharides have been isolated from the products of mild acid hydrolysis of the specific substance from Lactobacillus casei, serological group C. 2. The major disaccharide is O-beta-d-glucopyranosyl-(1-->3)-N-acetyl- d-galactosamine (B4) and evidence is presented for the structure of a tetrasaccharide composed of O-beta-d-glucopyranosyl-(1-->6)-d-galactose (B1) joined through its reducing end group to B4. 3. Disaccharide B1 is also a component of a trisaccharide O-beta-d-glucopyranosyl-(1-->6)-O-beta- d-galactopyranosyl-(1-->6)-N-acetyl-d-glucosamine (A7). 4. A number of other oligosaccharides have been shown to be related structurally. 5. The ability of certain of the oligosaccharides to inhibit the precipitin reaction has been studied. The disaccharide B1 is more effective as an inhibitor than gentiobiose and the trisaccharide A7 is considerably more effective than B1. 6. These results have been compared with those obtained previously for the composition of the cell wall.