Search Results
Abstract
It has been suggested that in ‘dry’ protein-trehalose-water systems, water-mediated hydrogen bond network, whose strength increases by drying, anchors the protein to its surroundings. To further characterize this effect, we performed a DSC study on low-water myoglobin-trehalose systems. The denaturation temperature resulted to increase by decreasing hydration, and linearly correlated to the glass transition temperature of both the ternary protein-water-trehalose and the binary water-trehalose systems. Further measurements are being performed to investigate eventual differences among different saccharides.
Abstract
Precipitation of trehalose dihydrate in water is observed at room temperature for trehalose concentrations higher than 47.5%w/w. Direct observations of crystal melting in water and measures of the solution density determine the thermal variations of trehalose saturationS(T) (mM) in water: ln(S(T))=ln(0.1223)-(1330/T) withR 2 =0.9982. The glass transition (Tg) curve measured by DSC is lower at low concentrations and higher at high concentrations than previously reported.T g is also measured as a function of the cooling/warming rates. Analysis of specific heat changes atT g and associated activation energy leads to identify a most stable glassy state around the second eutectic concentration.
Trehalose dihydrate, on careful dehydration below its fusion point, retains its original crystal facets but becomes X-ray amorphous, an unusual example of direct crystal-to-glass transformation. From DSC studies, the glass obtained by this route seems to be of abnormally low enthalpy, but after an initial scan, the normal form of glass transition is exhibited, withT g=115‡C, a higher value than previously reported. We give a preliminary thermal and mechanical characterization of this material and find it to be a very fragile liquid. The highT g is shown to rationalize the exceptionally high water content of the trehalose+water solution that vitrifies at ambient temperature (i.e.T g=298 K), and hence helps explain its use by Nature as a desiccation protectant. The spontaneous vitrification of crystalline materials during desolvation is related to the phenomenology of pressure-induced or decompression-induced vitrification of crystals via the concept of limiting metastability.
The present study was conducted to examine the protective role of arginine and trehalose on post-thaw bull sperm and oxidative stress parameters. Five ejaculates for each bull were used in the study. Each ejaculate, split into three equal aliquots and diluted at 37 °C with base extenders containing 2 mM arginine, 25 mM trehalose and no antioxidant (control) was cooled to 5 °C and then frozen. Frozen straws were thawed in a water bath for evaluation. Supplementation of the semen extender with arginine decreased the percentages of post-thawed subjective motility (29 ± 8.21%), CASA motility (12.2 ± 5.69%) and progressive motility (3.52 ± 2.13%), compared with the controls (43 ± 2.73%, 55.4 ± 6.78% and 33.48 ± 4.14%, respectively, P < 0.05). Supplementation of the semen extender with trehalose produced a higher mitochondrial activity and sperm viability (36.3 ± 3.99% and 44.1 ± 2.18%) compared with the control (13 ± 8.15 and 31.7 ± 3.94%, respectively, P < 0.05). It was established that trehalose (95.1%) and arginine (92.8%) protect DNA integrity compared to the control (90.4%) (P < 0.05). Trehalose supplementation in semen extenders provided great benefit in terms of viability, mitochondrial activity, and intact sperm DNA on frozen-thawed bull sperm.
Abstract
The phase transitions of α,α-trehalose dihydrate (T h) were investigated by either differential thermal analysis (DTA) with an in-house apparatus of variable-pressure type equipped with an open sample holder or commercially available TG (thermal gravimetry)-DTA apparatus for comparison under the same experimental conditions as to the heating rate (2°C min−1), the type of pan (open), and the particle size of T h (63 μm). The former DTA measurements were carried out under five different total pressures, 101, 75, 61, 48 and 35 kPa, which provided quite helpful information necessary for confirmative assignments of the endothermic peaks due to either melting or dehydration of T h. The usage of largely different amount of T h, 126 and 14 mg for the DTA and TG-DTA measurements respectively, led to their different DTA traces, showing that there were largely different extents of the influence by the measured sample surface exposed to the surrounding atmosphere on its dehydration behavior. In addition the high thermal sensitivity achieved with such mass of T h gave rise to an interesting discovery of an unidentified thermal event at 92°C prior to either melting or dehydration of T h.
constitute about 90% of water-soluble proteins of the lens and contribute to the transparency and refractive properties by forming a uniform concentration gradient in the lens [ 3 ]. Trehalose, a disaccharide formed by alpha-1,1 linkage of two d
Abstract
As trehalose is a glucose font and also an additive in food, a new reliable method for trehalose determination is proposed. The analytical method uses an isothermal microcalorimeter, directly relates the analyte concentration with the heat variation of the enzymatic decomposition of trehalose into two glucose molecules. The enzymatic reaction is performed inside the calorimeter in the presence of trehalase enzyme immobilized on amino activated glass beads. Through the calibration curve, the trehalose quantity in some food samples (mushrooms and honey) has been determined. The calorimetric procedure was compared to a previously identified methodology based on an amperometric biosensor.
Morchella conica Pers. strains of the study were isolated from fruit bodies collected in ash-mixed forests. At first, the strains were cultured on potato dextrose agar (PDA), then on modified Murashige and Skoog (MS*) solid agar media. A normal-growing strain was chosen for the trehalase induction experiments. During the trehalase induction treatment, mycelia were grown in liquid culture containing different concentrations of trehalose. After the induction period of trehalase enzymes, physiological state of the mycelium and the oxidative stress were monitored in the vegetative mycelia by measuring the change of the malondialdehyde content, superoxide dismutase enzyme activity, the fresh and dry weight. The examined Morchella conica strain utilized the trehalose properly. The rising amount of the trehalose triggered the increase of the mycelial trehalase enzyme activity. Our results clearly proved that both neutral and acidic trehalase isoenzyme activity of the Morchella conica mycelium are inducible and are playing important role in the utilization of external trehalose.
Sour cherry puree was prepared with addition of sucrose or trehalose (5% and 10%). After stabilization of the mixture (puree with sugars), extracts were prepared and contents of phenolics and anthocyanin, polymeric colour percentage, and antioxidant activity were determined. Extracts were stored for 65 days at 4 °C. Control sample was extract of sour cherry puree without sugars. After extraction, extracts with 10% of sucrose or trehalose had higher phenolic content than the control sample. Anthocyanin content was higher in extracts with trehalose addition. During storage of extracts, samples with trehalose had higher retention of phenolic and anthocyanins than other samples. Addition of sucrose and trehalose as well as their amounts affected the stabilities of phenolics, anthocyanins, and antioxidant activity in sour cherry extracts.
Abstract
Dehydration of trehalose dihydrate implemented by slow heating (1 K min−1), has been monitored by Raman microspectroscopy from 25 to 110�C directly on single crystals. Between 90 and 120�C, gas initially trapped in irregular macroscopic defects, reorganizes to form spherical vacuoles. The Raman analysis of these vacuoles highlights that the areas in vicinity of the defects are the first affected by the dehydration mechanisms. Indeed, the progressive amorphization of the crystal starts around these defects.
