Systematic assessment of the stability of benzaldehyde lyase in aqueous–organic biphasic systems and its stabilization by modification with methoxy-poly(ethylene) glycol

Coevolving stability and activity of LsCR by a single point mutation and constructing neat substrate bioreaction system

Carbonyl reductase (CR)-catalyzed bioreduction in the organic phase and the neat substrate reaction system is a lasting challenge, placing higher requirements on the performance of enzymes. Protein engineering is an effective method to enhance the properties of enzymes for industrial applications. In the present work, a single point mutation E145A on our previously constructed CR mutant LsCR_M3 , coevolved thermostability, and activity. Compared with LsCR_M3 , the catalytic efficiency k_cat /K_M of LsCR_M3 -E145A (LsCR_M4 ) was increased from 6.6 to 21.9 s^-1  mM^-1 . Moreover, E145A prolonged the half-life t_1/2 at 40°C from 4.1 to 117 h, T m ${T}_{m}$ was increased by 5°C, T 50 30 ${T}_{50}^{30}$ was increased by 14.6°C, and T_opt was increased by 15°C. Only 1 g/L of lyophilized Escherichia coli cells expressing LsCR_M4 completely reduced up to 600 g/L 2-chloro-1-(3,4-difluorophenyl)ethanone (CFPO) within 13 h at 45°C, yielding the corresponding (1S)-2-chloro-1-(3,4-difluorophenyl)ethanol ((S)-CFPL) in 99.5% ee_P , with a space-time yield of 1.0 kg/L d, the substrate to catalyst ratios (S/C) of 600 g/g. Compared with LsCR_M3 , the substrate loading was increased by 50%, with the S/C increased by 14 times. Compared with LsCR_WT , the substrate loading was increased by 6.5 times. In contrast, LsCR_M4 completely converted 600 g/L CFPO within 12 h in the neat substrate bioreaction system.

Enzyme-Loaded Mesoporous Silica Particles with Tuning Wettability as a Pickering Catalyst for Enhancing Biocatalysis

Pickering emulsion systems have created new opportunities for two-phase biocatalysis, however their catalytic performance is often hindered by biphasic mass transfer process relying on the interfacial area. In this study, lipase-immobilized mesoporous silica particles (LMSPs) are employed as both Pickering stabilizers and biocatalysts. A series of alkyl silanes with the different carbon length are used to modify LMSPs to obtain suitable wettability and enlarge the interfacial area of Pickering emulsion. The results show the water/paraffin oil Pickering emulsions stabilized by 8 carbon atoms silane grafted LMSPs (LMSPs_C8) with a three-phase contact angles of 95° get the relatively large interfacial area. Moreover, the conversion of enzymatic reaction catalyzed by LMSPs_C8 Pickering emulsion system is 3.4 times higher than that unmodified LMSPs with the reaction time of 10 min. Additionally, the effective recycling of LMSPs is achieved by simple low-speed centrifugation. As evidenced by a 6-cycles reaction of remaining 75% of relative enzymatic activity, the protection of 350–450 nm mesoporous silica particles can alleviate the inactivation of enzyme from the shear stress and make a benefit to form stabile Pickering emulsion. Therefore, the biphasic reactions in the Pickering emulsion system can be effectively enhanced through changing interfacial area only by the means of adjusting the wettability of biocatalysts.

Tailor-made catalytically active inclusion bodies for different applications in biocatalysis

CatIB properties can be tailored to the requirements of different reaction systems using two different coiled-coil domains as fusion tags.

CC bond formation using ThDP-dependent lyases

The present review summarizes recent achievements in enzymatic thiamine catalysis during the past three years. With well-established enzymes such as BAL, PDC and TK new reactions have been identified and respective variants were prepared, which enable access to stereoisomeric products. Further we highlight recent progress with 'new' ThDP-dependent enzymes like MenD and PigD, which catalyze the Stetter-like 1,4 addition of aldehydes and YerE, which is the first known ThDP-dependent enzyme accepting ketones as acceptors.

Nanoparticle cages for enzyme catalysis in organic media

Encapsulation of enzymes in Pickering emulsions results in a large interfacial area of the enzyme-containing aqueous phase for biocatalysis in organic media. This immobilization technique minimizes enzyme inactivation through stabilizing immiscible liquids by particles, facilitates separation processes, and significantly increases catalytic performance of both stable and vulnerable enzymes. Thus, a broad technical applicability can be envisioned.