Mapping out the Degree of Freedom of Hosted Enzymes in Confined Spatial Environments

The integration of enzymes with solid materials is crucial for promoting their industrialization. Understanding the enzyme behavior upon association within a confined space, though of fundamental importance for biocomposite development, remains a persistent, unresolved challenge. Here, we present a comprehensive elucidation of the spatial environment's impact on hosted enzymes' degree of freedom and, consequently, their accompanying reactivity. Site-directed spin labeling in combination with electron paramagnetic resonance spectroscopy allows the direct detection of host-guest interactions at atomic resolution, while the tailorable synthesis of covalent organic frameworks (COFs) enables an evaluation of factors affecting such interactions. Specifically, lysozyme is found to be more constrained and less active along with increasing hydrophilicity of the COFs. These results support the establishment of a connection between the hydrophilicity of the spatial environment and the resulting biocomposites' reactivity, enabling the prediction of the performance of unknown biocomposites. This study provides a unique insight into the mechanistic pathways underpinning biocatalysis.