| Abstract |
Predicting protein fold thermodynamics in diverse solution environments often relies on analyzing the transfer free energy (TFE) of individual amino acids. The longstanding utility of this concept lies in its capacity to elucidate the influence of osmolytes on protein fold and conformation, especially in the case of osmolytes that stabilize protein fold during stress. This phenomenon, known as the “osmophobic effect,” hinges on the capacity of specific osmolytes to exert repulsive forces on the peptide backbone, thereby maintaining protein fold. In contrast, relatively little is known about osmolyte effects on disordered and self-assembling proteins. This study explores TFE as a tool for uncovering synergistic osmolyte-disordered protein relationships, particularly during desiccation stress. In vitro enzyme assays and in vivo cell survival experiments reveal that trehalose and sucrose, osmolytes repulsive to many intrinsically disordered proteins (IDPs), significantly enhance IDP protection during desiccation. This protection correlates with increased radius of gyration and self-assembly in some proteins. Conversely, the attractive osmolyte betaine exhibits antagonistic effects. Our results underscore the crucial role of chemical environments in shaping IDPs and demonstrate the predictive power of thermodynamics in elucidating these interactions. This study represents one of the first connections between TFE and structure/function relationships in IDPs and offers a potential scheme for the optimization of protein-disaccharide mixtures as protective excipients. |
