Search results for " Seconda"
showing 10 items of 975 documents
Inactivation and structural changes of polyphenol oxidase in quince ( Cydonia oblonga Miller) juice subjected to ultrasonic treatment
2020
Background Polyphenol oxidase (PPO) is considered a problem in the food industry because it starts browning reactions during fruit and vegetable processing. Ultrasonic treatment is a technology used to inactivate the enzyme; however, the mechanism behind PPO inactivation is still unclear. For this reason, the inactivation, aggregation, and structural changes in PPO from quince juice subjected to ultrasonic treatments were investigated. Different intensities and times of ultrasonic treatment were used. Changes in the activity, aggregation, conformation, and structure of PPO were investigated through different structural analyses. Results Compared to untreated juice, the PPO activity in treat…
Calorimetric and structural investigation of the interaction between bovine serum albumin and high molecular weight dextran in water.
2005
This work studies specific interactions between a small globular protein and a highly flexible, branched polysaccharide using differential scanning calorimetry (DSC), circular dichroism (CD), fluorescence, and turbidimetry measurements. It uses the system water/bovine serum albumin (BSA)/dextran (D 2000) as a model. Dextran molecules are able to form interpolymeric complexes with BSA in water at both low and high temperatures if the polysaccharide is in excess and if the protein exists in its associated state. It leads to a partial destabilization of the secondary and tertiary structures of the protein and an additional exposure of the hydrophobic tryptophan residues to the surface of globu…
Existence of metastable intermediate lysozyme conformation highlights the role of alcohols in altering protein stability.
2011
Alcohols have a manifold effect on the conformational and thermodynamic stability of native proteins. Here, we study the effect of moderate concentrations of trifluoroethanol (TFE) on the thermal stability of hen egg-white lysozyme (HEWL), by far-UV circular dichroism and by steady-state and time-resolved photoluminescence of intrinsic tryptophans. Our results highlight that TFE affects lysozyme stability by preferential solvation of the protein molecule. Furthermore, we discovered the existence at 20% TFE of an equilibrium partially folded state of lysozyme, intermediate between the native and the unfolded state. A three-state model is therefore used to interpolate the thermal denaturation…
Thermal aggregation and ion-induced cold-gelation of bovine serum albumin
2009
Protein cold-gelation has recently received particular attention for its relevance in bio and food technology. In this work, we report a study on bovine serum albumin cold-gelation induced by copper or zinc ions. Metal-induced cold-gelation of proteins requires two steps: during the first one, the heat treatment causes protein partial unfolding and aggregation; then, after cooling the solution to room temperature, gels are formed upon the addition of metal ions. The thermally induced behaviour has been mainly investigated through different techniques: Fourier transform infrared (FTIR) spectroscopy, circular dichroism, dynamic light scattering (DLS) and rheology. Data have shown that the agg…
Two Latent and Two Hyperstable Polymeric Forms of Human Neuroserpin
2010
AbstractHuman neuroserpin (hNS) is a serine protease inhibitor that belongs to the serpin superfamily and is expressed in nervous tissues. The serpin fold is generally characterized by a long exposed loop, termed the reactive center loop, that acts as bait for the target protease. Intramolecular insertion of the reactive center loop into the main serpin β-sheet leads to the serpin latent form. As with other known serpins, hNS pathological mutants have been shown to accumulate as polymers composed of quasi-native protein molecules. Although hNS polymerization has been intensely studied, a general agreement about serpin polymer organization is still lacking. Here we report a biophysical chara…
Isolation and characterization of haemoporin, an abundant haemolymph protein from Aplysia californica.
2003
In the present study, we show the isolation and characterization of the protein haemoporin, which constitutes the second most abundant protein fraction in the haemolymph of the marine gastropod Aplysia californica. Although Aplysia is commonly used to investigate the molecular basis of learning, not much is known about the proteins in its haemolymph, which is in contact with the neurons owing to the open circulatory system of molluscs. In the native state, haemoporin is a macromolecular complex forming a cylinder with a central solvent-filled pore. The native complex most probably is a homopentamer made up from 70 kDa subunits with a molecular mass of 360 kDa and a sedimentation coefficient…
La dynamique des scolarités des filles : le double handicap questionné
2001
Marie Duru-Bellat, Annick Kieffer, Catherine Marry : Die Dynamik der Schullaufbahn der Mädchen : die Befragung des Doppelhindernisses. Dieser Aufsatz zeichnet die Entwicklung der geschlechtlichen und sozialen Unterschiede in der Schule seit Beginn des 20. Jahrhunderts auf, im Lichte des schulischen und wirtschaftlichen Felds. Er stützt sich auf die Daten der Untersuchungen Formation-Qualification Professionnelle des statistischen Amts INSEE. Die Geschichte der Schullaufbahnen der Jungen und Mädchen ist die der Aufholung durch die Mädchen, und schliesslich der Umkehr zu ihren Gunsten der Ungleichheiten zum Eintritt in die verschiedenen Stufen des ersten und zweiten Zyklus des höheren Schulwe…
La psychologie des environnements sociaux de la classe " et son applicabilité en France
2012
Ce séminaire porte sur l'examen des travaux qui s'inscrivent dans le cadre de " la Psychologie des environnements sociaux de la classe ", ayant pour finalité l'optimisation du climat social de la classe. Nous présentons des bilans d'études internationales, et des résultats personnels obtenus en France à l'école élémentaire et au collège, en fonction de trois principaux objectifs de la dite perspective. Ces derniers consistent à déterminer : 1) le climat social de classe qui favorisent le bon développement de tous les élèves, 2) les facteurs physico-environnementaux qui sont fondateurs du climat, et 3) la nature du climat de classe qui est le plus bénéfique à chaque type d'élèves (dont ceux …
Utilisation et validité du questionnaire "Learning environment inventory (LEI)" dans les classes de lycée
2020
International audience
Note critique de "l'efficacité des collèges, sociologie de l'effet établissement", d'Olivier Cousin
1999
International audience