Preparation of cross-linked enzyme aggregates in water-in-oil emulsion: Application to trehalose synthase

Immobilization of catalase on functionalized magnetic nanoparticles: a statistical approach

Magnetic nanoparticles (MNPs) Fe₃O₄, by virtue of easily modifiable surface, high surface-to-mass ratio and super-paramagnetic properties, are one of suitable candidates for the enzyme immobilization. Optimization of five important variables viz. concentration of 3-aminopropyl-tri-ethoxy-silane (APTES), glutaraldehyde (GA) and enzyme, time and temperature of loading was carried out using central composite type of experimental design without blocks giving 50 experiments including eight replicates at the central point. Characterization, stability and reusability studies were also carried out with optimized preparation. Results established the correlation between observed and response surface method (RSM) equation envisaged value (R ² 0.99, 0.97 and 0.98 for enzyme's activity, its loading over MNPs and corresponding specific activity, respectively. The predicted values suggested by RSM equation were 64.00 mM of APTES, 10.97 µL of GA, 14.50 mg mL^-1 of enzyme for 67 min at 22.6 °C, resulted in activity 32.1 U mg^-1 MNPs, while specific activity was 97.7 U mg^-1. Transmission electron microscopy (TEM) showed the sizes of MNPs (10.5 ± 1.7 nm), APTES-MNPs (10.23 ± 1.74 nm), GA-APTES-MNPs (11.84 ± 1.49 nm) and Catalase-GA-APTES-MNPs (13.32 ± 2.74 nm) were statistically similar. The enzyme MNPs preparation retained 81.65% activity after 144 h at 4 °C (free enzyme retained 7.87%) and 64.34% activity after 20 reuse cycles. Statistical optimized MNPs-based catalase preparation with high activity and magnetic strength was stable and can be used for further studies related to its application as analytical recyclable enzyme or magnetically oriented delivery in the body.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03173-8.

Efficiently Enantioselective Hydrogenation Photosynthesis of (R)-1-[3,5-Bis(trifluoromethyl)phenyl] ethanol over a CLEs-TiO2 Bioinorganic Hybrid Materials

Engineering of biological pathways with man-made materials provides inspiring blueprints for sustainable drug production. (R)-1-[3,5-Bis(trifluoromethyl)phenyl]ethanol [(R)-3,5-BTPE], as an important artificial chiral intermediate for complicated pharmaceutical drugs and biologically active molecules, is often synthesized through a hydrogenation reaction of 3,5-bis(trifluoromethyl)acetophenone (3,5-BTAP), in which enantioselectivity and sufficient active hydrogen are the key to restricting the reaction. In this work, a biohybrid photocatalytic hydrogenation system based on an artificial cross-linked enzymes (CLEs)-TiO₂-Cp*Rh(bpy) photoenzyme is developed through a bottom-up engineering strategy. Here, TiO₂ nanotubes in the presence of Cp*Rh(bpy) are used to transform NADP⁺ to NADPH during the formation of chiral alcohol intermediates from the catalytic reduction of a ketone substrate by alcohol dehydrogenase CLEs. Hydrogen and electrons, provided by water and photocatalytic systems, respectively, are transferred to reduce NADP⁺ to NADPH via [Cp*Rh(bpy)(H₂O)]²⁺. With the resulting NADPH, [(R)-3,5-BTPE] is synthesized using our efficient CLEs obtained from the cell lysate by nonstandard amino acid modification. Through this biohybrid photocatalytic system, the photoenzyme-catalyzed combined reductive synthesis of [(R)-3,5-BTPE] has a yield of 41.2% after reaction for 24 h and a very high enantiomeric excess value (>99.99%). In the case of reuse, this biohybrid system retained nearly 95% of its initial catalytic activity for synthesizing the above chiral alcohol. The excellent reusability of the CLEs and TiO₂ nanotubes hybrid catalytic materials highlights the environmental friendliness of (R)-3,5-BTPE production.

Techniques for Preparation of Cross-Linked Enzyme Aggregates and Their Applications in Bioconversions

Enzymes are biocatalysts. They are useful in environmentally friendly production processes and have high potential for industrial applications. However, because of problems with operational stability, cost, and catalytic efficiency, many enzymatic processes have limited applications. The use of cross-linked enzyme aggregates (CLEAs) has been introduced as an effective carrier-free immobilization method. This immobilization method is attractive because it is simple and robust, and unpurified enzymes can be used. Coimmobilization of different enzymes can be achieved. CLEAs generally show high catalytic activities, good storage and operational stabilities, and good reusability. In this review, we summarize techniques for the preparation of CLEAs for use as biocatalysts. Some important applications of these techniques in chemical synthesis and environmental applications are also included. CLEAs provide feasible and efficient techniques for improving the properties of immobilized enzymes for use in industrial applications.

A new cross-linked enzyme aggregate biocatalyst for NAD+-booster production

Cross-linked enzyme aggregates of NMN deamidase were produced with enhanced stability and reusability to obtain nicotinic acid mononucleotide.

Trehalose enhancing microbial electrolysis cell for hydrogen generation in low temperature (0 °C)

This work explored the feasibility of a method combining physical (sonication and base) and biological (partial fermentation) processes for sludge treatment and the effects of trehalose on the hydrogen generation of microbial electrolysis cell at 0 °C. The results demonstrated that the above pretreatment method was favorable, which promoted organics decomposing into lower molecular weight matter. The promotion of trehalose for MEC efficiency was obvious and the optimal concentration of trehalose was 50 mmol/L. With this concentration, the highest hydrogen recovery rate was 0.25 m(3)-H₂/-m(3)-reactor per day. Coulomb efficiency and energy recovery efficiency were 46.4% and 203%, respectively. Further, the consumption order of mixed substances was VFAs>proteins>carbohydrates. For microorganism community, SEM photographs illustrated that the selectivity of environmental temperature for the species of anode bacteria was strong and denaturing gradient gel electrophoresis indicated that Microbacterium and Proteobacteria were the two main species and Proteobacteria may be one of the species that produced electrons.