title: Dynamics and rigidity in an intrinsically disordered protein, β-casein.
abstract: The emergence of intrinsically disordered proteins (IDPs) as a recognized structural class has forced the community to confront a new paradigm of structure, dynamics, and mechanical properties for proteins. We present novel data on the similarities and differences in the dynamics and nanomechanical properties of IDPs and other biomacromolecules on the picosecond time scale. An IDP, β-casein (CAS), has been studied in a calcium bound and unbound state using neutron and light scattering techniques. We show that CAS partially folds and stiffens upon calcium binding, but in the unfolded state, it is softer than folded proteins such as green fluorescence protein (GFP). We also see that some localized diffusive motions in CAS have a larger amplitude than in GFP at this time scale but are still smaller than those observed in tRNA. In spite of these differences, CAS dynamics are consistent with the classes of motions seen in folded protein on this time scale.
authors.affiliation: Joint Institute for Neutron Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: Stefania
authors.initials: S
authors.lastname: Perticaroli
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Nickels
authors.forename: Georg
authors.initials: G
authors.lastname: Ehlers
authors.forename: Eugene
authors.initials: E
authors.lastname: Mamontov
authors.forename: Alexei P
authors.initials: AP
authors.lastname: Sokolov
mesh_terms: D000818:Animals; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D002364:Caseins / Q000737:chemistry* / Q000378:metabolism; D002417:Cattle; D055119:Elastic Modulus; D064267:Intrinsically Disordered Proteins / Q000737:chemistry / Q000378:metabolism; D008027:Light; D008892:Milk / Q000378:metabolism; D033363:Neutron Diffraction; D011485:Protein Binding; D011489:Protein Denaturation; D017433:Protein Structure, Secondary; D012542:Scattering, Radiation; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature
chemical_list: D002364:Caseins; D064267:Intrinsically Disordered Proteins; D002118:Calcium