Locking the Ultrasound-Induced Active Conformation of Metalloenzymes in Metal-Organic Frameworks

Enhancing the enzymatic activity inside metal- organic frameworks (MOFs) is a critical challenge in chemical technology and bio-technology, which, if addressed, will broaden their scope in energy, food, environmental, and pharmaceutical industries. Here, we report a simple yet versatile and effective strategy to optimize biocatalytic activity by using MOFs to rapidly lock the ultrasound (US)-activated but more fragile conformation of metalloenzymes. The results demonstrate that up to 5.3-fold and 9.3-fold biocatalytic activity enhancement of the free and MOFimmobilized enzymes could be achieved compared to those without US pretreatment, respectively. Using horseradish peroxidase as a model, molecular dynamics simulation demonstrates that the improved activity of the enzyme is driven by an opened gate conformation of the heme active site, which allows more efficient substrate binding to the enzyme. The intact heme active site is confirmed by solid-state UV-vis and electron paramagnetic resonance, while the US-induced enzyme conformation change is confirmed by circular dichroism spectroscopy and Fourier-transform infrared spectroscopy. In addition, the improved activity of the biocomposites does not compromise their stability upon heating or exposure to organic solvent and a digestion cocktail. This rapid locking and immobilization strategy of the US-induced active enzyme conformation in MOFs gives rise to new possibilities for the exploitation of highly efficient biocatalysts for diverse applications.

Automated summary

This study presents a simple and effective strategy to optimize the biocatalytic activity of metal-organic frameworks (MOFs) by utilizing ultrasound-activated enzyme conformation. The results demonstrate a significant enhancement in enzyme activity when compared to enzymes without ultrasound treatment. Molecular dynamics simulation and experimental validation support that the improved activity is attributed to a conformational change in the enzyme's active site. Furthermore, this strategy does not compromise the stability of the biocomposites when exposed to various conditions.