title: Aggregation behavior of bovine κ- and β-casein studied with small angle neutron scattering, light scattering, and cryogenic transmission electron microscopy.
abstract: In the native bovine casein micelle the calcium sensitive caseins (α(S1)-, α(S2)- and β-casein) sequester amorphous calcium phosphate in nanometer-sized clusters, whereas the calcium-insensitive κ-casein limits the growth of the micelle. In this paper, we further investigate the self-association of κ- and β-casein, which are two of the key proteins that control the substructure of the milk casein micelle, using neutron and light scattering techniques and cryogenic transmission electron microscopy. Results demonstrate that κ-casein can, apart from the known self-assembly, form amyloid-like fibrils already at temperatures of 25 °C when subject to agitation. This extended aggregation behavior of κ-casein is inhibited by β-casein, as reported by others. These findings have implications for the structure and stability of casein micelles. The neutron scattering data was used to gain information on the self-assembly structure of κ-casein. β-Casein shows similar self-association behavior as κ-casein, but unlike κ-casein, the self-association exhibits temperature dependence within the studied temperatures (6 and 25 °C). Here, we will discuss our extended study of the known self-assembly of casein in the context of the fibrillation of κ-casein.
authors.affiliation: Division of Physical Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden. sofie.ossowski@esss.se
authors.forename: Sofie
authors.initials: S
authors.lastname: Ossowski
authors.forename: Andrew
authors.initials: A
authors.lastname: Jackson
authors.forename: Marc
authors.initials: M
authors.lastname: Obiols-Rabasa
authors.forename: Carl
authors.initials: C
authors.lastname: Holt
authors.forename: Samuel
authors.initials: S
authors.lastname: Lenton
authors.forename: Lionel
authors.initials: L
authors.lastname: Porcar
authors.forename: Marie
authors.initials: M
authors.lastname: Paulsson
authors.forename: Tommy
authors.initials: T
authors.lastname: Nylander
mesh_terms: D000818:Animals; D002364:Caseins / Q000737:chemistry*; D002417:Cattle; D008027:Light; D046529:Microscopy, Electron, Transmission; D012542:Scattering, Radiation; D013696:Temperature
chemical_list: D002364:Caseins