Nanoscopic Dynamics Dictate the Phase Separation Behavior of Intrinsically Disordered Proteins.

Many intrinsically disordered proteins (IDPs) in nature may undergo liquid-liquid phase separation to assemble membraneless organelles with varied liquid-like properties and stability/dynamics. While solubility changes underlie these properties, little is known about hydration dynamics in phase-separating IDPs. Here, by studying IDP polymers of similar composition but distinct liquid-like dynamics and stability upon separation, namely, thermal hysteresis, we probe at a nanoscopic level hydration/dehydration dynamics in IDPs as they reversibly switch between phase separation states.

Characterization of Aqueous Lower-Polarity Solvation Shells Around Amphiphilic 2,2,6,6-Tetramethylpiperidine-1-oxyl Radicals in Water.

Solvation of the amphiphilic nitroxide radical 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and hydrophilic 4-oxo-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPONE) in water and tetrahydrofuran (THF) is studied in detail. The existence of pure water shells enclosing TEMPO in an aqueous solution that leads to significantly reduced local polarity at the nitroxide moiety is shown with multifrequency electron paramagnetic resonance (EPR) spectroscopy at X- and Q-bands as well as spectral simulations. These aqueous lower-polarity solvation shells (ALPSS) offer TEMPO a local polarity that is similar to that in organic solvents like THF.

Nanoscopic hydrophilic/hydrophilic phase-separation well below the LCST of polyphosphoesters.

The complex phase separation process of thermoresponsive polyphosphoesters (PPEs) with an identical side-group structure but different copolymer compositions is characterized by electron paramagnetic resonance (EPR) spectroscopy. In water these PPEs show LCST-type behavior, in which water-rich and slightly polymer-enriched nanoscopic regions are highly water swollen, and nanoscopic inhomogeneities with the lowest polarity contrast measured so far develop 8 °C below the macroscopic cloud point.