Small-angle neutron scattering (SANS) has been used to study effects of freezing and freeze-drying on proteins, by monitoring changes in protein interaction peak The proposed study is a continuation of LS-2793, in which pharmaceutical proteins were studied by small- and wide-angle X-ray scattering (SAXS/ WAXS) during freezing and thawing. [2]. The aims of the proposed study are (i) to investigate role of freeze-concentration vs. ice/solution interfaces on protein/protein interaction, using time- and temperature-resolved SAXS/WAXS measurements; and (ii) to study evolution of protein structure and protein/protein interaction during rehydration of freeze-dried protein/sugar powders. Pharmaceutically relevant proteins will be utilized.