Search results for " Second"
showing 10 items of 1396 documents
Amino acids in the second transmembrane helix of the Lhca4 subunit are important for formation of stable heterodimeric light-harvesting complex LHCI-…
2007
Photosynthetic light-harvesting complexes (LHCs) are assembled from apoproteins (Lhc proteins) and non-covalently attached pigments. Despite a considerable amino acid sequence identity, these proteins differ in their oligomerization behavior. To identify the amino acid residues determining the heterodimerization of Lhca1 and Lhca4 to form LHCI-730, we mutated the poorly conserved second transmembrane helix of the two subunits. Mutated genes were expressed in Escherichia coli and the resultant proteins were refolded in vitro and subsequently analyzed by gel electrophoresis. Replacement of the entire second helix in Lhca4 by the one of Lhca3 abolished heterodimerization, whereas it had no eff…
Localization of the N-terminal Domain in Light-harvesting Chlorophyll a/b Protein by EPR Measurements
2005
The conformational distribution of the N-terminal domain of the major light-harvesting chlorophyll a/b protein (LHCIIb) has been characterized by electron-electron double resonance yielding distances between spin labels placed in various domains of the protein. Distance distributions involving residue 3 near the N terminus turned out to be bimodal, revealing that this domain, which is involved in regulatory functions such as balancing the energy flow through photosystems (PS) I and II, exists in at least two conformational states. Models of the conformational sub-ensembles were generated on the basis of experimental distance restraints from measurements on LHCIIb monomers and then checked f…
Secondaire-supérieur
2008
Même si le lien entre le niveau de diplôme obtenu et la qualité de l'insertion professionnelle n'est pas parfait, posséder un diplôme de l'enseignement supérieur est un atout majeur à l'entrée sur le marché du travail. Cependant, alors qu'une des spécificités françaises du système d'enseignement supérieur est son caractère relativement différencié, son accès reste relativement typé socialement selon les distinctions qualitatives qu'il permet. Ces distinctions qualitatives, dans un contexte où l'accès aux différents niveaux d'enseignement s'est démocratisé, ne sont pas sans incidence sur l'insertion. Afin de comprendre les différences d'accès à l'enseignement supérieur et à ses types de curs…
Comportement des bacheliers : modèle de choix de disciplines
1979
The paper tries to take into account the choices taken by the high school graduates at the time of their immatriculation in higher education. The purpose is not a statistical description, but an attempt to test theoretical hypothesis of the individual behaviour. The analytical framework is based on the trade-off carried out by every student between the economical attractiveness of the different fields of education and professional careers which are linked on one hand, and the personal probability of success in every field on the other hand. In a first section, success models are estimated in various disciplines to get estimations of the objective chances of success for every student in ever…
S'orienter et élaborer un projet au sein d'un système hiérarchisé, une injonctoin paradoxale ? L'exemple du choix de la série et de l'enseignement de…
1997
The French "lycée" (higher secondary school), pupils are faced with successive subjects choices, and with the choice of Baccalauréat's speciality. This paper investigates from empirical data how these choices are progressively generated, along time and under which academic and social mechanisms. Those academic subjects choices prove to be influenced less by educational factors than by the concern to optimize one's schooling career. As long as the different routes are perceived as a hierarchy, and if concern for distinction and utilitarism are prevailing, the relevance of the notion of project has to be questionned.
Cytogenetic study of angiosarcoma of the breast.
1994
Angiosarcoma of the breast is quite rare, and the development of cutaneous angiosarcoma after segmental mastectomy and radiation therapy is even less common. A cytogenetic analysis of a mammary angiosarcoma arising in a breast after previous irradiation and segmental mastectomy for infiltrating ductal carcinoma revealed multiple clonal rearrangements involving chromosomes X, 1, 2, 3, 4, 5, 6, 7, 8, 9, 15, 17, 20, and 22. No cytogenetically analyzed angiosarcomas of the breast have been reported before. Genes Chromosom Cancer 10:210–212 (1994). © 1994 Wiley-Liss, Inc.
Fluorescence and circular dichroism spectroscopy to understand the interactions between cyclodextrins and α-galactosidase from green coffee beans
2017
Abstract The potential of fluorescence measurement and circular dichroism spectroscopy (CDSP) to evaluate the interaction between cyclodextrins (CDs) (CD cavity size, concentration, pH, reaction time, and temperature as well as different side chain groups) and α-galactosidase was evaluated. A strong relationship was observed between α-galactosidase fluorescence intensity and CD cavity size, concentration, pH, reaction time, and temperature as well as different side chain groups. Therefore, it can be concluded that fluorescence intensity measurement can be a promising tool to ascertain β-CD-α-galactosidase interactions. CDSP is also an interesting tool to understand β-CD-α-galactosidase inte…
Entrapment of A Beta 1-40 peptide in unstructured aggregates
2012
Recognizing the complexity of the fibrillogenesis process provides a solid ground for the development of therapeutic strategies aimed at preventing or inhibiting protein-protein aggregation. Under this perspective, it is meaningful to identify the possible aggregation pathways and their relative products. We found that Aβ-peptide dissolved in a pH 7.4 solution at small peptide concentration and low ionic strength forms globular aggregates without typical amyloid β-conformation. ThT binding kinetics was used to monitor aggregate formation. Circular dichroism spectroscopy, AFM imaging, static and dynamic light scattering were used for structural and morphological characterization of the aggre…
Irreversible formation of intermediate BSA oligomers requires and induces conformational changes.
2004
Understanding the relation between protein conformational changes and aggregation, and the physical mechanisms leading to such processes, is of primary importance, due to its direct relation to a vast class of severe pathologies. Growing evidence also suggests that oligomeric intermediates, which may occur early in the aggregation pathway, can be themselves pathogenic. The possible cytotoxicity of oligomers of non-disease-associated proteins adds generality to such suggestion and to the interest of studies of oligomer formation. Here we study the early stages of aggregation of Bovine Serum Albumin (BSA), a non pathogenic protein which has proved to be a useful model system. Dynamic light sc…
Protein/lipid coaggregates are formed during α-synuclein-induced disruption of lipid bilayers.
2014
Amyloid formation is associated with neurodegenerative diseases such as Parkinson's disease (PD). Significant α-synuclein (αSN) deposition in lipid-rich Lewy bodies is a hallmark of PD. Nonetheless, an unraveling of the connection between neurodegeneration and amyloid fibrils, including the molecular mechanisms behind potential amyloid-mediated toxic effects, is still missing. Interaction between amyloid aggregates and the lipid cell membrane is expected to play a key role in the disease progress. Here, we present experimental data based on hybrid analysis of two-photon-microscopy, solution small-angle X-ray scattering and circular dichroism data. Data show in real time changes in liposome …