Protein Internal Dynamics Associated With Pre-System Glass Transition Temperature Endothermic Events: Investigation of Insulin and Human Growth Hormone by Solid State Hydrogen/Deuterium Exchange.

Lyophilized proteins are generally stored below their glass transition temperature (T) to maintain long-term stability. Some proteins in the (pure) solid state showed a distinct endotherm at a temperature well below the glass transition, designated as a pre-T endotherm. The pre-T endothermic event has been linked with a transition in protein internal mobility.

Using the fluorescence red edge effect to assess the long-term stability of lyophilized protein formulations.

Nanosecond relaxation processes in sugar matrices are causally linked through diffusional processes to protein stability in lyophilized formulations. Long-term protein degradation rates track mean-squared displacement (⟨u(2)⟩) of hydrogen atoms in sugar glasses, a parameter describing dynamics on a time scale of picoseconds to nanoseconds. However, measurements of ⟨u(2)⟩ are usually performed by neutron scattering, which is not conducive to rapid formulation screening in early development.