Co-Immobilization and Co-Localization of Multi-Enzyme Systems on Porous Materials

Site-Specific and Tunable Co-immobilization of Proteins onto Magnetic Nanoparticles via Spy Chemistry

Co-immobilization of multiple proteins onto one nanosupport has large potential in mimicking natural multiprotein complexes and constructing efficient cascade biocatalytic systems. However, control of different proteins regarding their spatial arrangement and loading ratio remains a big challenge, and protein co-immobilization often requires the use of purified proteins. Herein, built upon our recently designed SpyTag-functionalized magnetic nanoparticles (MNPs), we established a modular MNP platform for site-specific, tunable, and cost-effective protein co-immobilization. SpyCatcher-fused enhanced green fluorescent protein (i.e., EGFP-SpyCatcher) and mCherry red fluorescent protein (i.e., RFP-SpyCatcher) were designed and conjugated on MNPs, and the immobilized proteins showed 3-7-fold enhancement in storage stability and greatly improved stability against the freeze-thaw process compared to free proteins. The protein-conjugated MNPs also retained desirable colloidal stability and magnetic responsiveness, enabling facile proteins' recovery. Also, one-pot co-immobilization of the two proteins could be fine-tuned with their feed ratios. In addition, MNPs could selectively and efficiently co-immobilize both SpyCatcher-fused proteins from combined cell lysates without purification, offering a convenient and cost-effective approach for multiprotein immobilization. This MNP platform provides a facile and efficient tool to construct bionano hybrid materials (i.e., protein-based MNPs) and multiprotein systems for a variety of industrial and green chemistry applications.

Simultaneous CO2 reduction and NADH regeneration using formate and glycerol dehydrogenase enzymes co-immobilized on modified natural zeolite

In this work, the co-immobilization of formate dehydrogenase (FDH) and glycerol dehydrogenase (GlyDH) enzymes is proposed to reduce CO₂ into formic acid, an important chemical intermediate. The reduction of carbon dioxide is carried out by FDH to obtain formic acid, simultaneously, the GlyDH regenerated the nicotinamide cofactor in the reduced form (NADH) by the oxidation of glycerol into dihydroxyacetone. Natural zeolite was selected as immobilization support given its good properties and low cost. The natural zeolite was modified with subsequent acid-alkaline attacks to obtain a mesostructurization of the clinoptilolite. The two enzymes were co-immobilized on clinoptilolite, previously hetero-functionalized with amino and glyoxyl groups. The distribution of the enzymes was confirmed by fluorescence microscopy analysis. Furthermore, a great increase in the retained activity for the formate dehydrogenase enzyme was noted, passing from 18% to 89%, when the mesostructured clinoptilolite was used as support. The immobilization yield of formate dehydrogenase and glycerol dehydrogenase is around 100% with all the supports studied. The promising results suggest a possible development of this procedure in enzyme immobilization and biocatalysis. The biocatalysts were characterized to find the optimal pH and temperature. Furthermore, a thermal stability test at 50 °C was carried out on both enzymes, in free and immobilized forms. Finally, it was shown that the biocatalyst is effective in reducing CO₂, both by using the cofactor in the reduced form (NADH) or the oxidized form (NAD⁺), obtaining NADH through the regeneration with glycerol in this latter case.

Is enzyme immobilization a mature discipline? Some critical considerations to capitalize on the benefits of immobilization

Enzyme immobilization has been developing since the 1960s and although many industrial biocatalytic processes use the technology to improve enzyme performance, still today we are far from full exploitation of the field. One clear reason is that many evaluate immobilization based on only a few experiments that are not always well-designed. In contrast to many other reviews on the subject, here we highlight the pitfalls of using incorrectly designed immobilization protocols and explain why in many cases sub-optimal results are obtained. We also describe solutions to overcome these challenges and come to the conclusion that recent developments in material science, bioprocess engineering and protein science continue to open new opportunities for the future. In this way, enzyme immobilization, far from being a mature discipline, remains as a subject of high interest and where intense research is still necessary to take full advantage of the possibilities.

One-Pot Purification and Immobilization of Phenylalanine Dehydrogenase from Bacillus nanhaiensi by Functional Reduced Graphene Oxide

The one-pot immobilization of halophilic phenylalanine dehydrogenase from marine microorganism with metal ions modified reduced graphene oxide (CRGO) material was studied. Phenylalanine dehydrogenase was from Bacillus nanhaiensi and expressed with a C-terminal His-tag. Investigation of CRGO, CRGO-PEI, CRCO-Mn, and CRGO-PEI-Mn for one-pot purification and immobilization of phenylalanine dehydrogenase from crude enzyme solution was carried out. Enzyme activity yield rate achieved 80.0% by immobilization with CRCO-Mn, and the loading capacity was 6.7 mg/mg. Manganese ion coordination greatly improved the selectivity of the CRGO for the target His-tagged enzyme. Furthermore, the effect of NaCl concentration on the immobilization was investigated, which the loading capacity of CRGO-PEI and CRGO-Mn-PEI was increased by 10.7% and 30.6% with 1 M NaCl, respectively. The adsorption curves of crude enzyme one-pot immobilized by CRGO-Mn and purified enzyme immobilized by CRGO-Mn were similar. Therefore, one-pot immobilization strategy is promising for industrial application with advantages such as high efficiency and low cost, which shorten the pipelines for enzyme discovery towards industrial applications through the establishing of marine enzyme collections.

Co-Immobilized Capillary Enzyme Reactor Based on Beta-Secretase1 and Acetylcholinesterase: A Model for Dual-Ligand Screening

We have developed a dual enzymatic system assay involving liquid chromatography-mass spectrometry (LC–MS) to screen AChE and BACE1 ligands. A fused silica capillary (30 cm × 0.1 mm i.d. × 0.362 mm e.d.) was used as solid support. The co-immobilization procedure encompassed two steps and random immobilization. The resulting huAChE+BACE1-ICER/MS was characterized by using acetylcholine (ACh) and JMV2236 as substrates. The best conditions for the dual enzymatic system assay were evaluated and compared to the conditions of the individual enzymatic system assays. Analysis was performed in series for each enzyme. The kinetic parameters (K_Mapp) and inhibition assays were evaluated. To validate the system, galantamine and a β-secretase inhibitor were employed as standard inhibitors, which confirmed that the developed screening assay was able to identify reference ligands and to provide quantitative parameters. The combination of these two enzymes in a single on-line system allowed possible multi-target inhibitors to be screened and identified. The innovative huAChE+BACE1-ICER/MS dual enzymatic system reported herein proved to be a reliable tool to identify and to characterize hit ligands for AChE and BACE1 in an enzymatic competitive environment. This innovative system assay involved lower costs; measured the product from enzymatic hydrolysis directly by MS; enabled immediate recovery of the enzymatic activity; showed specificity, selectivity, and sensitivity; and mimicked the cellular process.

Nature Inspired Multienzyme Immobilization: Strategies and Concepts

In a biological system, the spatiotemporal arrangement of enzymes in a dense cellular milieu, subcellular compartments, membrane-associated enzyme complexes on cell surfaces, scaffold-organized proteins, protein clusters, and modular enzymes have presented many paradigms for possible multienzyme immobilization designs that were adapted artificially. In metabolic channeling, the catalytic sites of participating enzymes are close enough to channelize the transient compound, creating a high local concentration of the metabolite and minimizing the interference of a competing pathway for the same precursor. Over the years, these phenomena had motivated researchers to make their immobilization approach naturally realistic by generating multienzyme fusion, cluster formation via affinity domain-ligand binding, cross-linking, conjugation on/in the biomolecular scaffold of the protein and nucleic acids, and self-assembly of amphiphilic molecules. This review begins with the discussion of substrate channeling strategies and recent empirical efforts to build it synthetically. After that, an elaborate discussion covering prevalent concepts related to the enhancement of immobilized enzymes' catalytic performance is presented. Further, the central part of the review summarizes the progress in nature motivated multienzyme assembly over the past decade. In this section, special attention has been rendered by classifying the nature-inspired strategies into three main categories: (i) multienzyme/domain complex mimic (scaffold-free), (ii) immobilization on the biomolecular scaffold, and (iii) compartmentalization. In particular, a detailed overview is correlated to the natural counterpart with advances made in the field. We have then discussed the beneficial account of coassembly of multienzymes and provided a synopsis of the essential parameters in the rational coimmobilization design.