Physical Isolation of Single Protein Molecules within Well-Defined Coordination Cages to Enhance Their Stability.

Encapsulation of a single protein within a confined space can lead to distinct properties compared to bulk solutions, but controlling the number of encapsulated proteins and their environment remains challenging. This study demonstrates the encapsulation of single proteins within well-defined, tunable cavities of self-assembled coordination cages, thereby enhancing protein stability. Within uniform cavities of size-tunable coordination cages, 15 different proteins of varying sizes (3-6 nm in diameter) and properties (e.

Hysteresis behavior in the unfolding/refolding processes of a protein trapped in metallo-cages.

Confinement of molecules in a synthetic host can physically isolate even their unstable temporary structures, which has potential for application to protein transient structure analysis. Here we report the NMR snapshot observation of protein unfolding and refolding processes by confining a target protein in a self-assembled coordination cage. With increasing acetonitrile content in CDCN/HO media (50 to 90 vol%), the folding structure of a protein sharply denatured at 83 vol%, clearly revealing the regions of initial unfolding.