Showing papers on "Melibiose published in 1998"

Determination of mono-, di-, and oligosaccharides in legumes by high-performance liquid chromatography using an amino-bonded silica column

Abstract: A high-performance liquid chromatography (HPLC) method for soluble sugars analysis, using an [[(aminopropyl)methyl]silyl]-bonded amorphous silica column, was applied to several dry legumes: chickpeas, lentils, white beans, pinto beans, and peas. Monosaccharide (ribose, fructose, glucose, and galactose), disaccharide (sucrose, maltose, and melibiose), and oligosaccharide (raffinose, ciceritol, and stachyose) composition of these samples was analyzed, with special interest on α-galactosides, because of their physiological role in inducing flatulent phenomena in humans after ingestion of legumes. Ciceritol (an inositol digalactoside) was the main sugar in chickpea samples and it was present also in lentils. In all the samples stachyose was found at higher levels than raffinose, and the content of these two flatulence-inducing sugars is higher in beans and lentils and lower in peas and chickpeas. However, great variability has been found in the sugar content of the different samples analyzed, probably due to...

Studies on the binding site of the galactose-specific agglutinin PA-IL from Pseudomonas aeruginosa.

Abstract: The binding properties of Pseudomonas aeruginosa agglutinin-I (PA-IL) with glycoproteins (gps) and polysaccharides were studied by both the biotin/avidin-mediated microtiter plate lectin-binding assay and the inhibition of agglutinin-glycan interaction with sugar ligands. Among 36 glycans tested for binding, PA-IL reacted best with two glycoproteins containing Galα1∀4Gal determinants and a human blood group ABO precursor equivalent gp, but this lectin reacted weakly or not at all with A and H active gps or sialylated gps. Among the mammalian disaccharides tested by the inhibition assay, the human blood group P k active Galα1∀ 4Gal, was the best. It was 7.4-fold less active than melibiose (Galα1∀6Glc). PA-IL has a preference for the α-anomer in decreasing order as follows: Galα1∀6 > Galα1∀ 4 > Galα1∀ 3. Of the monosaccharides studied, the phenylβ derivatives of Gal were much better inhibitors than the methylβ derivative, while only an insignificant difference was found between the Galα anomer of methyl- and pNO2-phenyl derivatives. From these results, it can be concluded that the combining size of the agglutinin is as large as a disaccharide of the α-anomer of Gal at nonreducing end and most complementary to Galα1∀6Glc. As for the combining site of PA-IL toward the β-anomer, the size is assumed to be less than that of Gal; carbon-6 in the pyranose form is essential, and hydrophobic interaction is important for binding.

The diversion of lactose carbon through the tagatose pathway reduces the intracellular fructose 1,6-bisphosphate and growth rate of Streptococcus bovis

Abstract: Twenty strains of Streptococcus bovis grew more slowly on lactose (1.21 ± 0.12 h−1) than on glucose (1.67 ± 0.12 h−1), and repeated transfers or prolonged growth in continuous culture (more than 200 generations each) did not enhance the growth rate on lactose. Lactose transport activity was poorly correlated with growth rate, and slow growth could not be explained by the ATP production rate (catabolic rate). Batch cultures growing on lactose always had less␣intracellular fructose 1,6-bisphosphate (Fru1,6P 2) than cells growing on glucose (6.6 mM compared to 16.7 mM), and this difference could be explained by the pathway of carbon metabolism. Glucose and the glucose moiety of lactose were metabolized by the Embden-Meyerhoff-Parnas (EMP) pathway, but the galactose moiety of lactose was catabolized by the tagatose pathway, a scheme that by-passed Fru1,6P 2. A mutant capable of co-metabolizing lactose and glucose grew more rapidly when glucose was added, even though the total rate of hexose fermentation did not change. Wild-type S. bovis grew rapidly with galactose and melibiose, but these galactose-containing sugars were activated by galactokinase and catabolized via EMP. On the basis of these results, rapid glycolytic flux through the EMP pathway is needed for the rapid growth (more than 1.2 h−1) of S.␣bovis.

Analysis of composition of sugar meals of wild mosquitoes by gas chromatography.

Abstract: Gas chromatography (GC) was successfully used for the first time to determine the components of natural sugar meals in individual mosquitoes and to determine whether carbohydrases are present in the crops of these insects. Crops of wild mosquitoes collected from a 2-ha cypress swamp north of Gainesville, FL, contained fructose, glucose, sucrose, maltose, turanose, melibiose, erlose, melezitose, raffinose, and a few unidentified carbohydrates. Time course studies with male and female Aedes albopictus showed rapid hydrolysis (> 90%) of sucrose occurring within 2 h of ingestion, whereas melezitose remained relatively unchanged even 8 h after ingestion. The crop extraction/GC analysis technique is an improvement over the cold anthrone test traditionally used for sugar analysis. This procedure is a rapid one-step process used to determine natural sugar sources, hydrolysis, occurrence, and preferences for individual wild sugar-feeding Diptera.

Effects of Carbohydrates on Levels of Total Glycogen and Protein in Adult Female Pimpla turionellae L.

Abstract: Effects of 22 carbohydrates belonging to various groups on the levels of total glycogen and protein in the adult female Pimpla turionellae L. were investigated. Sucrose was used as control in all experiments. Among the tested carbohydrates, xylose, ribose, rhamnose, mannose, maltose, cellobiose, melesitose, raffinose, glycogen, dulcitol and mannitol caused significant decreases on total glycogen level, but arabinose, fructose, galactose, glucose, sorbose, lactose, melibiose, trehalose, starch, sorbitol and a-methyl-d-glucoside did not any significant effect. The levels of total protein of the insect was increased by xylose, while it was decreased by glucose. The other carbohydrates tested did not cause any significant effect on total protein level of the insects.

Mutants of Citrobacter freundii That Transport and Utilize Melibiose

Abstract: We have isolated mutants of Citrobacter freundii that can grow on melibiose. Inducible alpha-galactosidase activity and melibiose transport activity were detected in the mutant cells but not in the wild-type cells. We detected a DNA region which hybridized with melB (the gene for the melibiose transporter) DNA of Escherichia coli in the chromosomal DNA of wild-type C. freundii. Protons, but not sodium ions, were found to be the coupling cations for melibiose (and methyl-beta-D-thiogalactoside) transport in the mutant cells.