Multi-strategy orthogonal enhancement and analysis of aldo-keto reductase thermal stability.

Given their outstanding efficiency and selectivity, enzymes are integral in various domains such as drug synthesis, the food industry, and environmental management. However, the inherent instability of natural enzymes limits their widespread industrial application. In this study, we underscore the efficacy of enhancing protein thermal stability through comprehensive protein design strategies, encompassing elements such as the free energy of protein folding, internal forces within proteins, and the overall structural design. We also demonstrate the efficiency and precision of combinatorial screening in the thermal stability design of aldo-keto reductase (AKR7-2-1). In our research, three single-point mutations and five combinatorial mutations were strategically introduced into AKR7-2-1, using multiple computational techniques. Notably, the E12I/S235I mutant showed a significant increase of 25.4 °C in its melting temperature (Tm). Furthermore, the optimal mutant, E12V/S235I, maintained 80 % of its activity while realizing a 16.8 °C elevation in Tm. Remarkably, its half-life at 50 °C was increased to twenty times that of the wild type. Structural analysis indicates that this enhanced thermal stability primarily arises from reduced oscillation in the loop region and increased internal hydrogen bonding. The promising results achieved with AKR7-2-1 demonstrate that our strategy could serve as a valuable reference for enhancing the thermal stability of other industrial enzymes.

Programmable and printable formaldehyde dehydrogenase as an excellent catalyst for biodegradation of formaldehyde.

As an environmental pollutant, formaldehyde can cause serious harm to the human body. Among many degradation methods, formaldehyde dehydrogenase from Pseudomonas putida (PFDH) exhibits broad potential because of its strong catalytic specificity and high degradation efficiency. However, the real application of PFDH in industry is limited by its instability and difficulties in recycling. In this work, the suitable printing conditions for immobilizing PFDH by three-dimensional (3D) printing technology were studied: the concentration of sodium alginate (SA) was 1.635 wt%, the concentration of CaCl2 was 7.4 wt%, the crosslinking time with CaCl2 was 8 min, and the temperature of the reaction was 31.5°C. 3D-printed PFDH/calcium alginate (CA) microspheres have 210% relative enzyme activity after seven repeated uses. Dried PFDH/CA particles were characterized by scanning electron microscope (SEM), Fourier transform infrared spectrometer (FT-IR), EDS elemental mapping, and thermogravimetric analysis (TGA) which proved that the enzyme was immobilized by the material. In addition, the recycling ability of 3D printing to immobilize different objects was explored and different shapes were designed by computer-aided design (CAD). In conclusion, 3D printing technology was applied to immobilize PFDH in this work, which provides a new idea to biodegrade formaldehyde in a green way.