Molecular Mobility in Dense Protein Systems: An Investigation through 1H NMR Relaxometry and Diffusometry

Antoine Bouchoux (1, 2) , Diane Schorr (3, 4) , Awa Daffé (3, 4) , Mireille Cambert (3, 4) , Geneviève Gésan-Guiziou (1) , François Mariette (3, 4)

1 STLO - Science et Technologie du Lait et de l'Oeuf
2 LGC - Laboratoire de Génie Chimique
3 UR TERE - Technologie des équipements agroalimentaires
4 UEB - Université européenne de Bretagne - European University of Brittany

Understanding how proteins behave in highly concentrated systems is a major issue in many fields of research, including biology, biophysics, and chemical engineering. In this paper, we provide a comprehensive 1H NMR study of molecular mobility in dilute to highly concentrateddispersions of the exact same protein (casein) but organized in two distinct supramolecular forms: spongelike casein micelles or soft casein aggregates. Both relaxometry and diffusometry experiments were performed, so that three different parameters are reported: spin−spin relaxation rates of non-water protons (1/T2,ne), spin−spin relaxation rates of water protons (1/T2,e+w), and water self-diffusion coefficients (Dw). The results are discussed in an effort to understand the respective effects of protein crowding and protein supramolecular organization on each mobility indicator. We also examine if connections exist between the observed changes in molecular mobility and the already documented changes in rheological and osmotic properties of casein dispersions as concentration is increased.

Mots clés: protéine; mobilité moléculaire; organisation; caséine; relaxométrie; diffusométrie

Domaines: Sciences du Vivant [q-bio]

Antoine Bouchoux, Diane Schorr, Awa Daffé, Mireille Cambert, Geneviève Gésan-Guiziou, et al.. Molecular Mobility in Dense Protein Systems: An Investigation through 1H NMR Relaxometry and Diffusometry. Journal of Physical Chemistry B, 2012, 116 (38), pp.11744-11753. ⟨10.1021/jp306078k⟩. ⟨hal-01209318⟩