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Poster De Conférence Année : 2011

Casein micelle internal structure : a sponge model

Résumé

By combining the osmotic stress technique with small-angle x-ray scattering measurements, we followed the structural response of the casein micelle to an overall increase in concentration. When the aqueous phase that separates the micelles is extracted, they behave as polydisperse repelling spheres and their internal structure is not affected. When they are compressed, the micelles lose water and shrink to a smaller volume. Our results indicate that this compression is nonaffine, i.e., some parts of the micelle collapse, whereas other parts resist deformation. We suggest that this behavior is consistent with a spongelike casein micelle having a triple hierarchical structure. The lowest level of the structure consists of the CaP nanoclusters that serve as anchors for the casein molecules. The intermediate level consists of 10- to 40-nm hard regions that resist compression and contain the nanoclusters. Those regions are connected and/or partially merged with each other, thus forming a continuous and porous material. The third level of structure is the casein micelle itself, with an average size of 100 nm. In our view, such a structure is consistent with the observation of 10- to 20-nm casein particles in the Golgi vesicles of lactating cells: upon aggregation, those particles would rearrange, fuse, and/or swell to form the spongelike micelle.
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Dates et versions

hal-01454369 , version 1 (02-02-2017)

Identifiants

  • HAL Id : hal-01454369 , version 1
  • PRODINRA : 201630

Citer

Antoine Bouchoux, Geneviève Gésan-Guiziou, J. Pérez, B. Cabane. Casein micelle internal structure : a sponge model. 5. Rencontres de Biologie Physique du Grand Ouest, Jun 2011, Rennes, France. 2011. ⟨hal-01454369⟩
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