posted on 2022-09-15, 17:40authored byJieying Liang, Muhammad Yazid Bin Zulkifli, Joel Yong, Zeping Du, Zhimin Ao, Aditya Rawal, Jason A. Scott, Jeffrey R. Harmer, Joseph Wang, Kang Liang
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 MOF-immobilized 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.