Search results for "trehalose"

Probing light-induced conformational transitions in bacterial photosynthetic reaction centers embedded in trehalose-water amorphous matrices.

2004

Abstract The coupling between electron transfer and protein dynamics has been studied in photosynthetic reaction centers (RC) from Rhodobacter sphaeroides by embedding the protein into room temperature solid trehalose–water matrices. Electron transfer kinetics from the primary quinone acceptor (Q A − ) to the photoxidized donor (P + ) were measured as a function of the duration of photoexcitation from 20 ns (laser flash) to more than 1 min. Decreasing the water content of the matrix down to ≈5×10 3 water molecules per RC causes a reversible four-times acceleration of P + Q A − recombination after the laser pulse. By comparing the broadly distributed kinetics observed under these conditions …

Myoglobin embedded in saccharide amorphous matrices: water-dependent domains evidenced by small angle X-ray scattering

2010

We report Small Angle X-ray Scattering (SAXS) measurements performed on samples of carboxy-myoglobin (MbCO) embedded in low-water trehalose glasses. Results showed that, in such samples, "low-protein" trehalose-water domains are present, surrounded by a protein-trehalose-water background; such finding is supported by Infrared Spectroscopy (FTIR) measurements. These domains, which do not appear in the absence of the protein and in analogous sucrose systems, preferentially incorporate the incoming water at the onset of rehydration, and disappear following large hydration. This observation suggests that, in organisms under anhydrobiosis, analogous domains could play a buffering role against th…

Do differences in chemical composition of stem and cap of Amanita muscaria fruiting bodies correlate with topsoil type?

2014

Fly agaric (Amanita muscaria) was investigated using a 1H NMR-based metabolomics approach. The caps and stems were studied separately, revealing different metabolic compositions. Additionally, multivariate data analyses of the fungal basidiomata and the type of soil were performed. Compared to the stems, A. muscaria caps exhibited higher concentrations of isoleucine, leucine, valine, alanine, aspartate, asparagine, threonine, lipids (mainly free fatty acids), choline, glycerophosphocholine (GPC), acetate, adenosine, uridine, 4-aminobutyrate, 6-hydroxynicotinate, quinolinate, UDP-carbohydrate and glycerol. Conversely, they exhibited lower concentrations of formate, fumarate, trehalose, α- an…

Thermal denaturation of myoglobin in water--disaccharide matrixes: relation with the glass transition of the system.

2009

Proteins embedded in glassy saccharide systems are protected against adverse environmental conditions [Crowe et al. Annu. Rev. Physiol. 1998, 60, 73-103]. To further characterize this process, we studied the relationship between the glass transition temperature of the protein-containing saccharide system (T(g)) and the temperature of thermal denaturation of the embedded protein (T(den)). To this end, we studied by differential scanning calorimetry the thermal denaturation of ferric myoglobin in water/disaccharide mixtures containing nonreducing (trehalose, sucrose) or reducing (maltose, lactose) disaccharides. All the samples studied are, at room temperature, liquid systems whose viscosity …

A reduction of protein specific motions in co-ligated myoglobin embedded in a trehalose glass

2000

Protein Thermal Denaturation and Matrix Glass Transition in Different Protein−Trehalose−Water Systems

2011

Biopreservation by saccharides is a widely studied issue due to its scientific and technological importance; in particular, ternary amorphous protein-saccharide-water systems are extensively exploited to model the characteristics of the in vivo biopreservation process. We present here a differential scanning calorimetry (DSC) study on amorphous trehalose-water systems with embedded different proteins (myoglobin, lysozyme, BSA, hemoglobin), which differ for charge, surface, and volume properties. In our study, the protein/trehalose molar ratio is kept constant at 1/40, while the water/sugar molar ratio is varied between 2 and 300; results are compared with those obtained for binary trehalose…

The three trehalases Nth1p, Nth2p and Ath1p participate in the mobilization of intracellular trehalose required for recovery from saline stress in Sa…

2009

Trehalose accumulation is a common response to several stresses in the yeast Saccharomyces cerevisiae. This metabolite protects proteins and membrane lipids from structural damage and helps cells to maintain integrity. Based on genetic studies, degradation of trehalose has been proposed as a required mechanism for growth recovery after stress, and the neutral trehalase Nth1p as the unique degradative activity involved. Here we constructed a collection of mutants for several trehalose metabolism and transport genes and analysed their growth and trehalose mobilization profiles during experiments of saline stress recovery. The behaviour of the triple ¿nth1¿nth2¿ath1 and quadruple ¿nth1¿nth2¿at…

The ATC1 gene encodes a cell wall-linked acid trehalase required for growth on trehalose in Candida albicans.

2004

After screening a Candida albicans genome data base, the product of an open reading frame (IPF 19760/CA2574) with 41% identity to Saccharomyces cerevisiae vacuolar acid trehalase (Ath1p) was identified and named Atc1p. The deduced amino acid sequence shows that Atc1p contains an N-terminal hydrophobic signal peptide and 20 potential sites for N-glycosylation. C. albicans homozygous mutants that lack acid trehalase activity were constructed by gene disruption at the two ATC chromosomal alleles. Analysis of these null mutants shows that Atc1p is localized in the cell wall and is required for growth on trehalose as a carbon source. An Atc1p endowed with acid trehalase activity was obtained by …

Acid trehalase is involved in intracellular trehalose mobilization during postdiauxic growth and severe saline stress in Saccharomyces cerevisiae.

2008

The role of the acid trehalase encoded by the ATH1 gene in the yeast Saccharomyces cerevisiae is still unclear. In this work, we investigated the regulation of ATH1 transcription and found a clear involvement of the protein kinase Hog1p in the induction of this gene under severe stress conditions, such as high salt. We also detected changes in the acid trehalase activity and trehalose levels, indicating a role of the acid trehalase in intracellular trehalose mobilization. Finally, the growth analysis for different mutants in neutral and acid trehalases after high salt stress implicates acid trehalase activity in saline stress resistance.

BSA Aggregation in Trehalose-Water Systems

2010

Introduction Recent studies [1] on ternary protein-trehalose-water samples have shown that the protein thermal denaturation temperature is linearly correlated with the glass transition temperature of the system, despite the quite large temperature difference between the two processes. In such studies it is stated that the collective, long range properties of the matrix that regulate the glass transition are strictly correlated with local features on which the denaturation of the protein depends. In order to ascertain whether an analogous correlation exists between the effects of trehalose on the protein’s aggregation process and the glass transition temperature of the system, we performed L…