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Reinforcement in nanocomposites with tunable structure: observation of chains in crowded environments
Auteur(s): Oberdisse J. , Tatou M., Banc A., Genix A.-C.
Conférence invité: Multi-scale Dynamics of Structured Polymeric Materials (Paris, FR, 2010-12-06)
Résumé: Reinforcement in nanocomposites with tunable structure: observation of chains in crowded environments
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Exploring the interactions of gliadins with model membranes: effect of confined geometry and interfaces. 
Auteur(s): Banc A., Desbat B., Renard Denis, Popineau Yves, Mangavel Cécile, Navailles Laurence
(Article) Publié:
Biopolymers, vol. 91 p.610 (2009)
Texte intégral en Openaccess : 
Ref HAL: hal-00550431_v1
PMID 19301297
DOI: 10.1002/bip.21188
WoS: 000267045000002
Exporter : BibTex | endNote
23 Citations
Résumé: Mechanisms leading to the assembly of wheat storage proteins into proteins bodies within the endoplasmic reticulum (ER) of endosperm cells are unresolved today. In this work, physical chemistry parameters which could be involved in these processes were explored. To model the confined environment of proteins within the ER, the dynamic behavior of gamma-gliadins inserted inside lyotropic lamellar phases was studied using FRAP experiments. The evolution of the diffusion coefficient as a function of the lamellar periodicity enabled to propose the hypothesis of an interaction between gamma-gliadins and membranes. This interaction was further studied with the help of phospholipid Langmuir monolayers. gamma- and omega-gliadins were injected under DMPC and DMPG monolayers and the two-dimensional (2D) systems were studied by Brewster angle microscopy (BAM), polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS), and surface tension measurements. Results showed that both gliadins adsorbed under phospholipid monolayers, considered as biological membrane models, and formed micrometer-sized domains at equilibrium. However, their thicknesses, probed by reflectance measurements, were different: omega-gliadins aggregates displayed a constant thickness, consistent with a monolayer, while the thickness of gamma-gliadins aggregates increased with the quantity of protein injected. These different behaviors could find some explanations in the difference of aminoacid sequence distribution: an alternate repeated - unrepeated domain within gamma-gliadin sequence, while one unique repeated domain was present within omega-gliadin sequence. All these findings enabled to propose a model of gliadins self-assembly via a membrane interface and to highlight the predominant role of wheat prolamin repeated domain in the membrane interaction. In the biological context, these results would mean that the repeated domain could be considered as an anchor for the interaction with the ER membrane and a nucleus point for the formation and growth of protein bodies within endosperm cells.
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Structure and Orientation Changes of ω-and γ-Gliadins at the Air-Water Interface : A PM-IRRAS Spectroscopy and Brewster Angle Microscopy Study
Auteur(s): Banc A., Desbat B., Renard Denis, Popineau Yves, Mangavel Cécile, Navailles Laurence
(Article) Publié:
Langmuir, vol. 23 p.13066 (2007)
Texte intégral en Openaccess :
Ref HAL: hal-00550429_v1
PMID 18031067
DOI: 10.1021/la702037k
WoS: 000251583000041
Exporter : BibTex | endNote
49 Citations
Résumé: Microscopic and molecular structures of ω- and γ-gliadin monolayers at the air-water interface were studied under compression by three complementary techniques: compression isotherms, polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS), and Brewster angle microscopy (BAM). For high molecular areas, gliadin films are homogeneous, and a flat orientation of secondary structures relative to the interface is observed. With increasing compression, the nature and orientation of secondary structures changed to minimize the interfacial area. The γ-gliadin film is the most stable at the air-water interface; its interfacial volume is constant with increasing compression, contrary to ω-gliadin films whose molecules are forced out of the interface. γ-Gliadin stability at a high level of compression is interpreted by a stacking model.
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