Search results for "SUCROSE"
showing 10 items of 178 documents
In vivoInvestigation of Plant-Cell Metabolism by means of natural-abundance13C-NMR spectroscopy
1994
Based on the natural abundance of 13C, in vivo13C-NMR was used for the first time to monitor the metabolism of sucrose and hydroquinone (1) in cell suspensions of the plant Rauwolfia serpentina (L.) BENTH. ex KURZ. Cells converted sucrose extracellularly into α-D- and β -D-glucose as well as into β -D-fructofuranose and β -D-fructopyranose, respectively. The sugar mixture was completely taken up by the cells after 4 days. Hydroquinone fed at that time resulted in optimum conversion into its β -D-glucoside arbutin (2) within 10 h. A further metabolite, the primeveroside (3) of hydroquinone, appeared as a trace compound after 10 h. The formation of this diglycoside can be increased by further…
A novel and simple method for the purification of extracellular levansucrase from Zymomonas mobilis.
2003
A new and simple method for the purification of extracellular levansucrase from Zymomonas mobilis from highly viscous fermentation broth was developed. After incubation of the fermentation broth with a fructose-polymer cleaving enzyme preparation (Fructozyme, Novozymes, DK) for 48 h, levansucrase precipitated as aggregates and was redissolved in a 3 M urea solution. By ongoing size-exclusion chromatography on Sephacryl S-300 the final levansucrase preparation was purified 100-fold and exhibited a specific activity of 25-35 U/mg(protein). The levansucrase was stable in 3 M urea solution for at least four months without inactivation. To maximize the enzyme yield the dynamic changes of extrace…
Mechanistic Understanding of Food Effects: Water Diffusivity in Gastrointestinal Tract Is an Important Parameter for the Prediction of Disintegration…
2013
Much interest has been expressed in this work on the role of water diffusivity in the release media as a new parameter for predicting drug release. NMR was used to measure water diffusivity in different media varying in their osmolality and viscosity. Water self-diffusion coefficients in sucrose, sodium chloride, and polymeric hydroxypropyl methylcellulose (HPMC) solutions were correlated with water uptake, disintegration, and drug release rates from trospium chloride immediate release tablets. The water diffusivity in sucrose solutions was significantly reduced compared to polymeric HPMC and molecular sodium chloride solutions. Water diffusivity was found to be a function of sucrose concen…
Effect of water on glass transition in starch/sucrose matrices investigated through positron annihilation lifetime spectroscopy: a new approach
2011
Glass transition is studied through positron annihilation lifetime spectroscopy (PALS) in maize starch matrices containing 10 (batch STS10) and 20 (STS20) w/w% sucrose, as a function of temperature (T) and water content (c(w)). To circumvent important losses of water upon heating while recording the PALS spectra, a new method is developed: instead of a series of measurements of τ(3), the triplet positronium lifetime, at different T, the latter is kept constant and the series relates to c(w), which is left to decrease at a constant rate. Similarly to the changes in τ(3) with T, the τ(3)vs. c(w) plots obtained show a smooth linear increase until a break, denoting the occurrence of glass trans…
Labile carbon alleviates wood ash effects on soil fauna
2008
The combined effects of wood ash, sucrose and oxalic acid on enchytraeid size and biomass, the abundance of microbial-feeding nematodes and pH were studied in a full three-factorial design in laboratory microcosms containing 30 g of Norway spruce forest humus. Wood ash treatment reduced enchytraeid size and abundance, but these effects were offset by sucrose without any change in pH or moisture. The positive effects of sucrose were partially counteracted by oxalic acid. Both carbon compounds increased the abundance of obligate microbial-feeding nematodes, indicating enhanced microbial production.
Direct Organogenesis from Cotyledons in Cultivars of Citrus clementina Hort. ex Tan
2011
An efficient protocol to induce shoot buds regeneration in Citrus clementina cultivars (“Monreal”, “SRA 63” and “SRA 64”) by direct organogenesis has been developed using cotyledons as explants. Cotyledons transversely cut in three segments and entire ones were cultured on Murashige and Skoog (1962) solidified medium containing vitamins, 500 mg·l−1 malt extract, 50 g·l−1 sucrose and supplemented with three different concentrations of BAP (8.8, 13.2 and 17.6 μM). In all three cultivars the entire cotyledons showed more shoot morphogenic potential than transversely cut ones and after 60 incubation days the optimum BAP concentration was 17.6 μM in “Monreal” (50% ± 2.89% of frequency regenerati…
Effect of Hormones on Sucrose Uptake and on ATPase Activity of Citrus sinensis L. Osbeck Leaves
1994
Carbohydrate accumulation in young, fully expanded leaves of Citrus sinensis L. Osbeck is affected by the presence of the fruitlet on the shoot. Previous work gave evidence that gibberellins may be involved in this 'fruit effect'. In the present work we have studied the effect of gibberellic acid (GA3) on 14C-sucrose uptake by leaf discs and whether its action could be due to a modulation of the plasma membrane ATPase, which maintains the H+ gradient that drives H+/sucrose co-transport. The effect of GA3 on 14C-sucrose uptake depended on the osmolarity of the assay medium. At 300 mOsm a reduction in the uptake rate was observed. The inhibitory effect of the hormone disappeared after preincu…
Freezing without surrounding cryomedium preserves the endothelium and its function in human internal mammary arteries
2005
Abstract Purpose Cryopreserved human blood vessels may become important tools in bypass surgery. Optimal cryopreservation of an arterial graft should, therefore, preserve both histological and physiological characteristics of smooth muscle and endothelium comparable to the unfrozen artery. Methods Rings from human internal mammary arteries (IMA) were investigated in vitro either unfrozen or after immersion into a cryomedium (RPMI 1640 containing 1.8 M Me2SO and 0.1 M sucrose) and cryostorage with and without surrounding medium. Results In unfrozen IMA, neither contractile responses to noradrenaline (NA) nor endothelium-dependent relaxant responses to acetylcholine (ACH) was modified after e…
Carbohydrate metabolism of vegetative and reproductive sinks in the late-maturing peach cultivar ‘Encore’
1999
Activities of NAD(+)-dependent sorbitol dehydrogenase (SDH), sorbitol oxidase (SOX), sucrose synthase (SS), acid invertase (AI), and neutral invertase (NI) in 'Encore' peach (Prunus persica L.) fruits and developing shoot tips were assayed during the growing season to determine whether carbohydrate metabolizing enzymes could serve as indicators of sink strength. In fruit flesh, SS activity was detected during Stage I of growth, when cells were actively dividing, and SDH activity was detected during Stage III, when cells were actively enlarging. Acid invertase activity was detected during Stage I and showed a closer correlation with relative increase in fruit weight during the growing season…