jp503788r_si_001.pdf (391.24 kB)
Dynamics and Rigidity in an Intrinsically Disordered Protein, β‑Casein
journal contribution
posted on 2014-07-03, 00:00 authored by Stefania Perticaroli, Jonathan D. Nickels, Georg Ehlers, Eugene Mamontov, Alexei P. SokolovThe 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.