Rangées de graines.. © INRA, Elena Schweitzer © Fotolia

Our results

Contents
  1. Introduction
  2. Human milk digestion in the preterm infant: impact of technological treatments
  3. Research & Innovation 2017 - For Food and Biobased Products
  4. The way in which proteins aggregate when heated may change their sensitising potency
  5. Enhancing the viability of spray-dried probiotic bacteria by stimulating their stress tolerance
  6. To stick or not to stick? Pulling pili sheds new light on biofilm formation
  7. When biopolymers selfassemble: a balance between energy and entropy.
  8. Mimicking the gastrointestinal digestion in a lab-on-a-chip:the microdigester
  9. How a milk droplet becomes a powder grain
  10. Research & Innovation 2016 - For Food and Bioproducts
  11. A new process for the biorefining of plants
  12. Under the UV light : the bacterial membrane
  13. Reverse engineering or how to rebuild ... bread!
  14. Green Chemistry: a step towards lipid production in yeast
  15. Individually designed neo-enzymes for antibacterial vaccines
  16. Multi-scale mechanical modelling: from the nanometric scale to the macroscopic properties of bread crumb
  17. Minimill: 500 g to assess the milling value of soft wheats
  18. Microbial production of lipids for energy or chemical purposes
  19. The discrete role of ferulic acid in the assembly of lignified cell wall
  20. Eco-design of composites made from wood co-products
  21. Analysis of volatile compounds enables the authentication of a poultry production system
  22. Nanoparticles as capping agents for biopolymers microscopy
  23. Pasteurisation, UHT, microfiltration...All the processes don't affect the nutritional quality of milk in the same way
  24. Integration of expert knowledge applied to cheese ripening
  25. Controlling cheese mass loss during ripening
  26. The shape memory of starch
  27. Research & Innovation 2015 - For Food & Biobased Products
  28. Behaviour of casein micelles during milk filtering operations
  29. Overaccumulation of lipids by the yeast S. cerevisiae for the production of biokerosine
  30. Sequential ventilation in cheese ripening rooms: 50% electrical energy savings
  31. An innovative process to extract bioactive compounds from wheat
  32. Diffusion weighted MRI: a generic tool for the microimaging of lipids in food matrices
  33. Characterization of a major gene of anthocyanin biosynthesis in grape berry
  34. New enzyme activity detectors made from semi-reflective biopolymer nanolayers
  35. Improving our knowledge about the structure of the casein micelle
  36. Heating milk seems to favour the development of allergy in infants
  37. Fun with Shape
  38. Using volatile metabolites in meat products to detect livestock contamination by environmental micropollutants
  39. SensinMouth, when taste makes sense
  40. A decision support system for the fresh fruit and vegetable chain based on a knowledge engineering approach
  41. SOLEIL casts light on the 3D structure of proteins responsible for the stabilisation of storage lipids in oilseed plants
  42. A close-up view of the multi-scale protein assembly process
  43. Controlling the drying of infant dairy products by taking water-constituent interactions into account
  44. Polysccharide nanocrystals to stabilise pickering emulsions
  45. Discovery of new degradative enzymes of plant polysaccharides in the human intestinal microbiome
  46. A durum wheat flour adapted for the production of traditional baguettes
  47. Virtual modelling to guide the construction of « tailored-made » enzymes
  48. How far can we reduce the salt content of cooked meat products?
  49. Diffusion of organic substances in polymer materials: beyond existing scaling laws
  50. Smart Foams : various ways to destroy foams on demand !
  51. Dates, rich in tannins and yet neither bitter nor astringent
  52. Sodium content reduction in food
  53. Research & Innovation 2014

A close-up view of the multi-scale protein assembly process

By working on two model proteins in mixture, lysozyme (LYS) and α-lactalbumine (LAC), and by combining multi-scale experimental approaches and modelling, researchers have revealed how information contained at the molecular scale is transferred to the microscopic scale, thus identifying the limiting stage in scale change. This fundamental information makes it possible to more effectively control assembly processes and to adapt them to targeted applications when necessary.

Orientation proteins and their assembly into micrometer structures. © INRA

The agri-food industry is more than ever confronted with the need to innovate in relation to the use of ingredients generated during food transformation processes

Among these ingredients, proteins are currently being targeted by research because of their high innovation potential.   The aim is to control the properties that they confer to finished products and, more and more, to develop new biomaterials (nano- or microparticles) provided with specific functionalities and properties that will act as the vector for the protection and targeted release of health-related molecules. Understanding the processes that govern protein assembly is a major challenge at the international level and a prerequisite to the development of these applications because it determines the control of the stability, morphology and final properties of the objects formed.

Within the framework of a thesis and an ANR project (LAclys)

 Researchers concentrated their efforts on determining why only the interaction of lysozyme with the decalcified form of α-lactalbumine (apo-LAC) leads to supramolecular objects whose morphology depends on temperature.  A multi-scale approach combining NMR, light diffusion, microscopy and molecular simulation was set up to address this issue and to understand how information contained at the molecular scale is transferred to the microscopic scale.  Researchers showed that LYS interacts with both the calcified and decalcified forms of LAC to form heterodimers.  However, only the apo-LAC/LYS heterodimers combine to form tetramers.  This association is made possible by a particular orientation of specific amino acids located at the interface of the two proteins. This orientation, confirmed by molecular simulation, is governed by the electrostatic attractions between the two dimers.  Thus, the formation of a tetramer is certainly the limiting step in the size scale change during the assembly process between the two proteins.  The growth of sub-micrometric particles from nuclei formed by the aggregation of tetramers is determined by collision and fusion of smaller particles.  It is at this final stage of the mechanism that the conformational state of apo-LAC plays an important role on the morphology of the objects formed.  In fact, the coalescence of the particles and the reorganisation of protein aggregates into microspheres are favoured by the flexibility of the decalcified form of LAC and probably involve hydrophobic associations.
The combination of the experimental and theoretical approaches implemented to carry out this research can be extended to the study of the mechanisms underlying the assembly process of other protein systems.  This will allow us to predict these processes on the basis of the intrinsic properties of different proteins present during the process.   Moreover, we have begun to study the fate of the self-assembly process of protein mixtures in the presence of different small molecules of biological or nutritional interest such as vitamins, fatty acids, polyphenols, etc.

Partnership

  • ANR Laclys (PNRA, 2008-2010) : Laboratory of Chemistry and Biology of Metals CEA, Grenoble ; Institut de Physique de Rennes ; GMPA, INRA Grignon
  • UMR CNRS Université du Maine, Polymères, Colloides, Interfaces, Le Mans
  • Department of Theoretical Chemistry, Université de Lund, Suède

Références

See also

  • D.B. Salvatore, T. Croguennec, V. Forge, S. Bouhallab, T. Nicolai (2011).  Kinetics and Structure during Self-Assembly of Oppositely Charged Proteins in Aqueous Solution. Biomacromolecules, 12 (5), 1920–1926.
  • D.B. Salvatore, N. Duraffourg, A. Favier, B.A. Persson, M. Lund, M.M. Delage, R. Silvers, H. Schwalbe, T. Croguennec, S.Bouhallab, V. Forge (2011). Investigation at Residue Level of the Early Steps during the Assembly of Two Proteins into Supramolecular Objects. Biomacromolecules, 12, 2200–2210.