Effects of water on the structure and low/high temperature stability of confined proteins

In this study well-characterized model proteins were confined in silica nanoporous matrices. Confinement of the proteins in silica matrices allowed us to explore the role of water hydrogen bonding on the structures of the proteins in a broad range of temperatures (-120 degrees C to 95 degrees C). At low temperatures confinement suppressed freezing of water, which remained in the liquid state. We obtained direct evidence that the changes in the hydrogen bonding of water induced changes in the structure of confined proteins. At high temperatures, a reduction of hydrogen bonding of water facilitated protein-silica interactions and the confined proteins underwent denaturation. However, the incorporation of the osmolyte, trehalose, reduced protein-silica interactions, and altered the hydrogen bonding of water. As a result, the high temperature thermal stability of the confined proteins was greatly improved.