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

Abstract

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.

Insight into Bioactivity of In‐situ Trapped Enzyme‐Covalent‐Organic Frameworks

“…However, the content of β‐sheet from HRP‐COF‐LZU1 is increased, whereas the content of β‐sheet from HRP‐RT‐COF‐1 and HRP‐ACOF‐1 is decreased, suggesting the HRP conformation in COF‐LZU1 is more favorable. the enzyme experienced significant structural alteration upon immobilization within reticular framework, although this structural change is generally not stable in its free form, as evidenced by our previous research that the reticular frameworks could lock this fragile conformation and improve the enzyme stability [4a] …”

“…Next, 2D 13 C− 1 H heteronuclear correlation (HETCOR) NMR measurement was conducted to probe the interaction between HRP and COFs. Incorporating a 10 ms 1 H− 1 H spin diffusion time prior to the transfer of signal from the 1 H to the 13 C nuclei enables the local ≈1–2 nm scale region around the detected 13 C species to be probed [4a, 24] . The contour plots in Figure 3d–f display cross‐correlation peaks between the 1 H NMR signals of the HRP (CH 3 /Hβ ≈1.8 ppm and Hα 3.5 ppm) and the 13 C species of the COFs (180 ppm‐100 ppm).…”

Heterogeneity in enzyme/metal–organic framework composites for CO2transformation reactions

“…The design, synthesis, characterization, and biocatalytic application of enzyme/MOF composites have been experiencing considerable growth recently. [5][6][7][8][9][10][11][12] Following their development, biocomposites have been synthesized via the orthogonal combination of various enzymes and MOFs. Enzyme immobilization can be realized via one-pot encapsulation in MOFs, infiltration in MOFs, or surface-bonding on a MOF crystallite.…”

Enhancing Enzyme Activity Using Hydrophilic Hollow Layered Double Hydroxides as Encapsulation Carriers

“…Enzyme immobilization, defined as the spatial restriction of an enzyme on solid carriers based on adsorption, covalent binding, and cross-linking, is an effective way to overcome these intrinsic demerits of enzymes and considerably facilitate the industrialization of biotechnology. , However, not all carriers and immobilization strategies can provide optimal advantages in the case of enzymes. Substantial challenges remain in this area, such as enzyme leakage, irreversible disruption of enzyme structure, and poor accessibility of the enzyme active sites. , The natural biomineralization-inspired in situ enzyme encapsulation strategy enables simultaneous enzyme immobilization and carrier synthes is under mild conditions, effectively overcoming the aforementioned shortcomings of traditional post-immobilization strategies. , In addition, the in situ encapsulation adapts to retain enzyme properties, overcomes enzyme size limitations, and addresses the issue of compromised enzyme sensitivity when subjected to harsh environments …”