Search results for "Trehalose"

On the biochemical classification of yeast trehalases: Candida albicans contains two enzymes with mixed features of neutral and acid trehalase activi…

2009

Abstract Two enzymes endowed with trehalase activity are present in Candida albicans . The cytosolic trehalase (Ntc1p), displayed high activity in exponential phase regardless of the carbon source (glucose, trehalose or glycerol). Ntc1p activity was similar in neutral (pH 7.1) or acid (pH 4.5) conditions, strongly inhibited by ATP, weakly stimulated by divalent cations (Ca 2+ or Mn 2+ ) and unaffected in the presence of cyclic AMP. The Ntc1p activity decreased in stationary phase, except in glycerol-grown cultures, but the catalytic properties did not change. In turn, the cell wall-linked trehalase (Atc1p) showed elevated activity in resting cells or in cultures growing on trehalose or glyc…

Immediate early response of the marine sponge Suberites domuncula to heat stress: Reduction of trehalose and glutathione concentrations and glutathio…

1997

The marine sponge Suberites domuncula was used to identify early markers for thermal stress. Cubes from sponges have been kept for 30 min at 31°C (10 °C higher than the ambient temperature). After this treatment the sponge cubes were kept again at 21°C. To demonstrate that the animals reacted to the elevated temperature, the expression of heat shock protein (HSP) was determined. Using an antibody raised against HSP70, it was found by Western blotting that the animals specifically express a 45 kDa polypeptide after heat treatment. It was shown that even after 10 min of heat treatment the steady-state concentration of trehalose drops by 40% from a base level of 13 nmol/mg protein. The activit…

MbCO embedded in trehalosyldextrin matrices: thermal effects and protein-matrix coupling

2010

Saccharide-based biopreservation is widely studied because of its scientific importance and possible technological outcomes for food and pharmaceutical industries. Ternary protein/saccharide/water systems have been extensively exploited to model the characteristics of the in vivo biopreservation process. A tight, water dependent, protein–matrix coupling has been shown to occur in various simple saccharide amorphous matrices, which is stronger in trehalose. The efficiency as bioprotectant of trehalose has been ascribed to this tight coupling, since the appearance of damages on biological structures will more involve structural variations of the surrounding matrix. Here we present, as an appl…

Impact of Starmerella bacillaris and Zygosaccharomyces bailii on ethanol reduction and Saccharomyces cerevisiae metabolism during mixed wine fermenta…

2021

AbstractThe bulk of grape juice fermentation is carried out by the yeast Saccharomyces cerevisiae, but non-Saccharomyces yeasts can modulate many sensorial aspects of the final products in ways not well understood. In this study, some of such non-conventional yeasts were screened as mixed starter cultures in a fermentation defined medium in both simultaneous and sequential inoculations. One strain of Starmerella bacillaris and another of Zygosaccharomyces bailii were chosen by their distinct phenotypic footprint and their ability to reduce ethanol levels at the end of fermentation, particularly during simultaneous vinification. S. bacillaris losses viability strongly at the end of mixed fer…

Interaction Between Osmotic and Hydrostatic Pressure in Yeast Inactivation

1999

The protective effect of an osmotic perturbation on high-pressure inactivation has been investigated using a yeast strain:Saccharomyces cerevisiae. Osmotic shocks have been carried out with binary medium (glycerol/sorbitol and water) with or without glucose. Variations of osmotic level, osmotic shift kinetics and time between osmotic and hydrostatic treatment (350 MPa/10 min) have allowed the characterization of cell baroprotection. Two different cumulative baroprotection effects have been distinguished: one conferred by the solute on biological structures and the other related to the osmotic stress, cell volume variations and stress metabolism response (HSP, trehalose). These experiments h…

Effect of protein net charge and steric hindrance on the glass transition of Protein-Trehalose-Water systems and on protein thermal denaturation

2010

Matrix glass transition and embedded protein denaturation: effect of trehalose on different proteins

2010

Structure−Dynamics Coupling between Protein and External Matrix in Sucrose-Coated and in Trehalose-Coated MbCO:  An FTIR Study

2004

We performed FTIR measurements on carboxy-myoglobin (MbCO) embedded in a sucrose−water matrix to study the degrees of freedom coupling between protein and external matrix in such a system. The work was undertaken on the light of recent results by Giuffrida et al. (J. Phys. Chem. B 2003, 107, 13211−13217), who evidenced, in trehalose-coated MbCO, a structured water−sugar environment of the protein, tightly coupled to the heme pocket structure. Such information was obtained through a suitable analysis of the temperature dependence of the CO stretching and of the water association bands in samples of different content of residual water. We applied here the same analysis to sucrose-coated MbCO.…

Ocular gelling microspheres: in vitro precorneal retention time and drug permeation through reconstituted corneal epithelium.

2008

Purpose: The model drug norfloxacin (NOR)was encapsulated into trehalose (TRH) and hydroxyethylcellulose(NAT) microspheres to obtain a novel gelling ophthalmic delivery system for prolonged release on corneal tissue. Methods: We assessed NOR release from microspheres, prepared by the emulsion-solvent evaporation method. A new in vitro tear turnover model, including inserts containing reconstituted human corneal epithelium (RHC), was designed to evaluate the TRH/NAT microspheres’ precorneal retention time. Bioadhesive properties of TRH/NAT microspheres were validated by using drug-loaded microspheres prepared with gelatine (GLT) commonly used as reference material in adhesion studies. Result…

More than a Confinement: “Soft” and “Hard” Enzyme Entrapment Modulates Biological Catalyst Function

2019

Catalysis makes chemical and biochemical reactions kinetically accessible. From a technological point of view, organic, inorganic, and biochemical catalysis is relevant for several applications, from industrial synthesis to biomedical, material, and food sciences. A heterogeneous catalyst, i.e., a catalyst confined in a different phase with respect to the reagents’ phase, requires either its physical confinement in an immobilization matrix or its physical adsorption on a surface. In this review, we will focus on the immobilization of biological catalysts, i.e., enzymes, by comparing hard and soft immobilization matrices and their effect on the modulation of the catalysts’ function. Indeed, …