title: Molecular mobility in dense protein systems: an investigation through 1H NMR relaxometry and diffusometry.
abstract: 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 (1)H NMR study of molecular mobility in dilute to highly concentrated dispersions 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/T(2,ne)), spin-spin relaxation rates of water protons (1/T(2,e+w)), and water self-diffusion coefficients (D(w)). 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.
authors.affiliation: INRA, UMR1253 Science et Technologie du Lait et de l'Œuf, F-35042 Rennes, France. antoine.bouchoux@rennes.inra.fr
authors.forename: Antoine
authors.initials: A
authors.lastname: Bouchoux
authors.forename: Diane
authors.initials: D
authors.lastname: Schorr
authors.forename: Awa
authors.initials: A
authors.lastname: Daffé
authors.forename: Mireille
authors.initials: M
authors.lastname: Cambert
authors.forename: Geneviève
authors.initials: G
authors.lastname: Gésan-Guiziou
authors.forename: François
authors.initials: F
authors.lastname: Mariette
mesh_terms: D002364:Caseins / Q000737:chemistry*; D004058:Diffusion; D008823:Micelles; D019906:Nuclear Magnetic Resonance, Biomolecular; D011522:Protons; D014867:Water / Q000737:chemistry
chemical_list: D002364:Caseins; D008823:Micelles; D011522:Protons; D014867:Water