Changes In Glycosidase Activities Research Articles

Changes in activities of glycosidases in the hemolymph of the silkworm, Bombyx mori, during larval development

Changes in activities of glycosidases in the hemolymph of the silkworm, Bombyx mori, during larval development

Salt-Adaptation of Tobacco BY2 Cells Induces Change in Glycoform ofN-Glycans: Enhancement of Exo- and Endo-Glycosidase Activities by Salt-Adaptation

In this report, we describe that a salt adaptation of plant cells induces glycoform changes in N-glycoproteins. Intracellular and cell-wall glycopeptides were prepared from glycoproteins expressed in wild-type BY2 cells and salt-adapted cells. N-Glycans were liberated from those glycopeptides by hydrazinolysis, and the released oligosaccharides were N-acetylated and pyridylaminated. The structures of pyridylaminated (PA-) N-glycans were analyzed by a combination of two-dimensional sugar-chain mapping, MS analysis, and exoglycosidase digestion. In both wild-type cells and salt-adapted cells, the plant complex type structure was predominant among N-glycans expressed on glycoproteins, but we found that the Man2Xyl1Fuc1GlcNAc2 structure was significantly expressed on intracellular and cell-wall glycoproteins of the salt-adapted cells. Furthermore, enhancement of the specific activities of alpha-mannosidase and beta-N-acetylglucosaminidase was observed in the salt-adapted BY2 cells, suggesting that the glycoform changes are due to changes in glycosidase activities.

Changes in glycosidase activities during galactoglucomannan oligosaccharide inhibition of auxin induced growth

The inhibition of 2,4-D-induced elongation growth by galactoglucomannan oligosaccharides (GGMOs) in pea stem segments ( Pisum sativum L. cv. Tyrkys) after 18 h of incubation results in changes of extracellular, intracellular and cell wall glycosidase activities (β- d-glucosidase, β- d-mannosidase, β- d-galactosidase, β- d-xylosidase, α- d-galactosidase, and α- l-arabinosidase). GGMOs lowered the glycosidase activities in the extracellular fraction, while in the cell wall fractions their activities were markedly increased. The intracellular enzyme α- d-galactosidase increased while the β- d-galactosidase decreased in activity in response to the GGMO treatment. Extracellular enzymes showed low values of activities in comparison with intracellular and cell wall glycosidases. It is evident that GGMOs can alter auxin induced elongation and glycosidase activities in different compartments of the cell, however, the mode and site of their action remains unclear.

Analysis of glycosidically bound aroma precursors in tea leaves. 2. Changes in glycoside contents and glycosidase activities in tea leaves during the black tea manufacturing process.

Glycosides are known to be precursors of the alcoholic aroma compounds of black tea. They are hydrolyzed by endogenous glycosidases during the manufacturing process. Changes in the amounts of these glycosides during the manufacturing process were investigated by using a capillary gas chromatographic--mass spectrometric analysis after trifluoroacetyl derivatization of the tea glycosidic fractions. Primeverosides were 3-fold more abundant than glucosides in fresh leaves, but they decreased greatly during the manufacturing process, especially during the stage of rolling. After the final stage of fermentation, primeverosides had almost disappeared, whereas glucosides were substantially unchanged. These results show that hydrolysis of the glycosides mainly occurred during the stage of rolling and confirm that primeverosides are the main black tea aroma precursors. This was also supported by the changes in the glycosidase activities in tea leaves. The glycosidase activities remained at a high level during withering but decreased drastically after rolling.

Glycosidase Activities of Three Enological Yeast Strains During Winemaking: Effect on the Terpenol Content of Muscat Wine

β-glucosidase, α-arabinosidase and α-rhamnosidase activities of three enological yeast strains (<i>Saccharomyces cerevisiae</i>) were monitored during fermentation of a Muscat of Frontignan grape juice. The enzyme activities, measured in the juice and the yeast biomass, reached their maximum during exponential growth of the yeast population, then dropped quickly. Changes in glycosidase activities were similar in all three yeast strains. β-glucosidase was the most abundant glycosidase and showed a poor stability at wine pH. The wines obtained from the different yeast strains contained similar levels of terpenols, and no significant differences were found in sensory analysis.

Changes in glycosidase activities during development and ripening of melon

Changes in the activity of several glycosidases were studied in mesocarp tissues of muskmelon (Cucumis melo L., var. Alpha) during fruit ontogeny. Mesocarp tissue contained α- and β-D-galactosidase, α-D-mannosidase, β-D-glucosidase, β-D-xylosidase, α-L-arabinopyranosidase and α-L-arabinofuranosidase activities at selected stages during fruit development. The activities of α-D-galactosidase and β-D-xylosidase did not change significantly during ripening. The activities of α-D-mannosidase and α-L-arabinofuranosidase increased slightly from the turning to the ripe stages, while those of β-D-galactosidase, α-L-arabinopyranosidase and β-D-glucosidase increased significantly from the turning to the overripe stages. When expressed on a protein basis, all activities measured increased at the turning stage, but only those of β-D-galactosidase, α-L-arabinopyranosidase and β-D-glucosidase continued until the end of ripening and overripeness. Glycosidases whose specific activities increased or remained constant during the final stages of ripeness were mainly solubilised in a high-ionic-strength-extractable fraction. In contrast, those whose specific activity decreased towards full ripening were mainly solubilised using a low-ionic-strength extractant. A possible role for glycosidases in muskmelon softening is discussed.

Changes in glycosidase activities in lectin resistant myogenesis-defective myoblast cell lines

1. 1. Mannosidase, hexosaminidase, galactosidase and fucosidase activities were determined in cell free extracts of wild type and con A-resistant L6 myoblast cells. 2. 2. Two mannosidase activities were detected, with pH optima of 4.6 and 6.0. The con A-resistant cells were almost devoid of intracellular mannosidase activity with optimum pH 4.6. Differences in K m and F max values for mannosidase activities were found when con A-resistant and wild type cells were compared. 3. 3. A decrease in the intracellular hexosaminidase activity in the con A-resistant myoblasts was accompanied by an increase in extracellular activity. N mannosidase activities of wild type and con A-resistant cells.

Changes in glycosidase activities in concanavalin a resistant and sensitive mammalian cells

1. 1. Mannosidase, fucosidase and hexosaminidase activities were determined in cell free preparations of concanavalin A resistant and sensitive Chinese hamster ovary cells. 2. 2. Two hexosaminidase activities were detected; one had an optimum pH of 4.2 and the other had an optimum pH of 6.3. 3. 3. The glycosidase activities were clearly dependent on growth conditions. When cells were grown on solid surfaces three significant changes occurred in glycosidase levels as cell density increased. The specific activity of the pH 4.2 hexosaminidase from concanavalin A-resistant cells decreased three fold; α- l fucosidase levels increased in wild type and revertant cells; and the α-mannosidase levels were significantly reduced in all three cell lines. 4. 4. Also supporting the view that glycosidases are responsive to growth conditions was the observation that the specific activities of glycosidases from cells shifted from growth on solid surfaces to suspension were markedly increased. 5. 5. Significant differences in glycosidase activities between lectin resistant and sensitive cells were observed indicating that these activities may be directly involved in determining the complex pleiotropic phenotype described for concanavalin A resistant cells.