Search results for "protéine"

III. Biochemistry of S-layers

1997

During evolution prokaryotes have developed different envelope structures exterior to the cell wall proper. Among these surface components are regularly arranged S-layers and capsules. The structural characterization and the detailed chemical analysis of these surface molecules is a prerequisite to understand their biosynthesis and functional role(s) at the molecular level. Of particular interest are the glycosylated S-layer proteins which belong to the first prokaryotic glycoproteins ever described. Their characterization was performed on strains belonging to the thermophilic Bacillaceae and included structural studies and experiments to learn about the pathways for the glycan biosynthesis…

Soybean and casein hydrolysates induce grapevine immune responses and resistance against Plasmopara viticola

2014

International audience; Plasmopara viticola, the causal agent of grapevine downy mildew, is one of the most devastating grape pathogen in Europe and North America. Although phytochemicals are used to control pathogen infections, the appearance of resistant strains and the concern for possible adverse effects on environment and human health are increasing the search for alternative strategies. In the present investigation, we successfully tested two protein hydrolysates from soybean (soy) and casein (cas) to trigger grapevine resistance against P. viticola. On Vitis vinifera cv. Marselan plants, the application of soy and cas reduced the infected leaf surface by 76 and 63%, as compared to th…

Plasma membrane protein trafficking in plant-microbe interactions: a plant cell point of view

2014

International audience; In order to ensure their physiological and cellular functions, plasma membrane (PM) proteins must be properly conveyed from their site of synthesis, i.e., the endoplasmic reticulum, to their final destination, the PM, through the secretory pathway. PM protein homeostasis also relies on recycling and/or degradation, two processes that are initiated by endocytosis. Vesicular membrane trafficking events to and from the PM have been shown to be altered when plant cells are exposed to mutualistic or pathogenic microbes. In this review, we will describe the fine-tune regulation of such alterations, and their consequence in PM protein activity. We will consider the formatio…

Early signaling events induced by elicitors of plant defenses

2006

International audience; Plant pathogen attacks are perceived through pathogenissued compounds or plant-derived molecules that elicit defense reactions. Despite the large variety of elicitors, general schemes for cellular elicitor signaling leading to plant resistance can be drawn. In this article, we review early signaling events that happen after elicitor perception, including reversible protein phosphorylations, changes in the activities of plasma membrane proteins, variations in free calcium concentrations in cytosol and nucleus, and production of nitric oxide and active oxygen species. These events occur within the first minutes to a few hours after elicitor perception. One specific eli…

The Recent Development of a Sweet-Tasting Brazzein and its Potential Industrial Applications

2016

International audience; Brazzein is a small heat- and pH-stable sweet-tasting protein isolated from the West African plant, Pentadiplandra brazzeana. Brazzein combines a highly sweet potency, a long history of human consumption, and a remarkable stability, giving it great potential as a natural sweetener. Due to the difficulties of obtaining brazzein from its natural source, several efforts have been made to express brazzein using various heterologous expression systems. This chapter describes the biochemical, structural, sensory, and physiological properties of brazzein. We will summarize the current knowledge of the structure-activity relationship of brazzein. The biotechnological product…

Place des protéines végétales en alimentation animale

2021

Study of the chemical, physical and functional properties of edible starch-based films

2016

The amount of waste increased annually, mainly from plastic industry. Plastic materials were more produced during the only last ten years than during the last millennium. A potential solution of the ecological and economic problems can be biodegradable or edible films and coatings. The goal of this thesis was to study edible films and coatings based on starch. Fifteen types of film-forming solutions were made: 3 types of starch, starch + different amounts of plasticizer, starch + proteins, starch + oil. To better understanding the interaction between film components, physical, chemical and functional tests were done. Finnaly, validation on real foods (plums) as coatings and films helped to …

Production, fonction et localisation d'Orchestine: calciprotéine spécifique de la matrice organique des structures minéralisées élaborées par le crus…

2002

As most Crustaceans, Orchestia cavimana possesses a mineralized exoskeleton which is periodically replaced. Because of the terrestrial behaviours of this animal, this molting cycle is related to calcium storage and resorption processes. Calcium storage occurs, as calcareous concretions, in diverticula of the midgut called posterior cæca. Calcareous concretions are essentially composed of amorphous calcium carbonate precipitated within a proteinaceous organic matrix composed of a soluble fraction and an insoluble one in an EDTA-buffer. Among the soluble components of the organic matrix, a previous study led to characterize a polypeptide of 23 kDa in SDS-PAGE called Orchestin. This protein, w…

Biomolecules and nanostructured systems : characterization by Surface Enhanced Raman Scattering (SERS)

2014

This work addressed the study of several kinds of nanostructured systems, biomolecules and inorganic thin films, mainly by Surface Enhanced Raman Spectroscopy (SERS). The aim was to investigate the structure and the chemical bonds. Transmission electron microscopy (TEM) was also used to complete the structural characterization of the different samples.Firstly, the study was conducted on molecules of biological interest. The aim was to study the interaction between silver nanoparticles and proteins. With this aim, silver nanoparticles bioconjugated with different proteins (hemoglobin, cytochrome C, BSA and lysozim) were synthesized. SERS results allowed concluding that proteins are chemisorb…

Upregulation of liver VLDL receptor and FAT/CD36 expressions in LDLR-/- apoB100/100 mice fed trans-10,cis-12 conjugated linoleic acid

2006

International audience; This study explores the mechanisms responsible for the fatty liver setup in mice fed trans-10,cis-12 conjugated linoleic acid (t10c12 CLA), hypothesizing that an induction of low density lipoprotein receptor (LDLR) expression is associated with lipid accumulation. To this end, the effects of t10c12 CLA treatment on lipid parameters, serum lipoproteins, and expression of liver lipid receptors were measured in LDLR(-/-) apoB(100/100) mice as a model of human familial hypercholesterolemia itself depleted of LDLR. Mice were fed t10c12 CLA over 2 or 4 weeks. We first observed that the treatment induced liver steatosis, even in the absence of LDLR. Mice treated for 2 weeks…