Glyoxyl agarose: A fully inert and hydrophilic support for immobilization and high stabilization of proteins

Recent Trends in Biomaterials for Immobilization of Lipases for Application in Non-Conventional Media

The utilization of biomaterials as novel carrier materials for lipase immobilization has been investigated by many research groups over recent years. Biomaterials such as agarose, starch, chitin, chitosan, cellulose, and their derivatives have been extensively studied since they are non-toxic materials, can be obtained from a wide range of sources and are easy to modify, due to the high variety of functional groups on their surfaces. However, although many lipases have been immobilized on biomaterials and have shown potential for application in biocatalysis, special features are required when the biocatalyst is used in non-conventional media, for example, in organic solvents, which are required for most reactions in organic synthesis. In this article, we discuss the use of biomaterials for lipase immobilization, highlighting recent developments in the synthesis and functionalization of biomaterials using different methods. Examples of effective strategies designed to result in improved activity and stability and drawbacks of the different immobilization protocols are discussed. Furthermore, the versatility of different biocatalysts for the production of compounds of interest in organic synthesis is also described.

Glyoxyl-Activated Agarose as Support for Covalently Link Novo-Pro D: Biocatalysts Performance in the Hydrolysis of Casein

This study aimed to evaluate the performance of a commercial protease (Novo-Pro D (NPD)), both in soluble and immobilized forms, in the hydrolysis of proteins (using casein as model protein). Immobilization of the protease NPD on 6% agarose activated with glyoxyl groups for 24 h at 20 °C and pH 10.0 allowed preparing immobilized biocatalyst with around 90% immobilization yield, 92% recovered activity versus small substrate, and a thermal stability 5.3-fold higher than the dialyzed soluble enzyme at 50 °C and pH 8.0. Immobilization times longer than 24 h lead to a decrease in the recovered activity and did not improve the biocatalyst stability. At 50 °C and pH 6.5, the immobilized NPD was around 20-fold more stable than the dialyzed soluble protease. Versus casein, the immobilized NDP presented a 10% level of activity, but it allowed hydrolyzing casein (26 g/L) at 50 °C and pH 6.5 up to a 40% degree of hydrolysis (DH) after 2 h reaction, while under the same conditions, only a 34% DH was achieved with soluble NPD. In addition, the immobilized NPD showed good reusability, maintaining the DH of casein for at least ten 2h-reaction batches.

Biocatalysis in the winemaking industry: Challenges and opportunities for immobilized enzymes

Enzymes are powerful catalysts already being used in a large number of industrial processes. Impressive advantages in enzyme catalysts improvement have occurred in recent years aiming to improve their performance under harsh operation conditions far away from those of their cellular habitat. Production levels of the winemaking industry have experienced a remarkable increase, and technological innovations have been introduced for increasing the efficiency at different process steps or for improving wine quality, which is a key issue in this industry. Enzymes, such as pectinases and proteases, have been traditionally used, and others, such as glycosidases, have been more recently introduced in the modern wine industry, and many dedicated studies refer to the improvement of enzyme performance under winemaking conditions. Within this framework, a thorough review on the role of enzymes in winemaking is presented, with special emphasis on the use of immobilized enzymes as a significant strategy for catalyst improvement within an industry in which enzymes play important roles that are to be reinforced paralleling innovation.

Efficient Biodiesel Production Catalyzed by Nanobioconjugate of Lipase from Pseudomonas fluorescens

The Amano lipase from Pseudomonas fluorescens (L-AK) was covalently immobilized on various carbon nanomaterials (functionalized single-walled carbon nanotubes and graphene oxide) and tested for biodiesel production. Using the most active lipase preparation (covalently immobilized L-AK on SwCNTNH2 derivatized with glycerol diglycidyl ether) under optimal conditions, quasi-complete conversion (>99%) of sunflower oil was obtained after only 4 h reaction time. Moreover, the biocatalyst maintained more than 99% of its initial activity in the batch system after multiple recycling experiments.

Parameters for the Evaluation of Immobilized Enzymes Under Process Conditions

The characterization of immobilized enzymes allows the evaluation of the immobilization process itself and also the projection of the immobilized enzyme performance under process operation conditions. Based on such characterization, strategies for support functionalization and enzyme immobilization into the activated support can be selected, determining the best conditions for conducting such steps in view of the intended use of the biocatalyst, establishing a linkage between biocatalyst production and biocatalyst use. The determination of the catalytic potential of the immobilized enzyme under operational conditions is a priceless parameter that takes into account both activity and stability, including the effect of both mass transfer limitations (diffusional restrictions) and intrinsic enzyme inactivation upon the immobilization process.

A Multi-Enzymatic Cascade Reaction for the Synthesis of Vidarabine 5′-Monophosphate

We here described a three-step multi-enzymatic reaction for the one-pot synthesis of vidarabine 5′-monophosphate (araA-MP), an antiviral drug, using arabinosyluracil (araU), adenine (Ade), and adenosine triphosphate (ATP) as precursors. To this aim, three enzymes involved in the biosynthesis of nucleosides and nucleotides were used in a cascade mode after immobilization: uridine phosphorylase from Clostridium perfringens (CpUP), a purine nucleoside phosphorylase from Aeromonas hydrophila (AhPNP), and deoxyadenosine kinase from Dictyostelium discoideum (DddAK). Specifically, CpUP catalyzes the phosphorolysis of araU thus generating uracil and α-d-arabinose-1-phosphate. AhPNP catalyzes the coupling between this latter compound and Ade to form araA (vidarabine). This nucleoside becomes the substrate of DddAK, which produces the 5′-mononucleotide counterpart (araA-MP) using ATP as the phosphate donor. Reaction conditions (i.e., medium, temperature, immobilization carriers) and biocatalyst stability have been balanced to achieve the highest conversion of vidarabine 5′-monophosphate (≥95.5%). The combination of the nucleoside phosphorylases twosome with deoxyadenosine kinase in a one-pot cascade allowed (i) a complete shift in the equilibrium-controlled synthesis of the nucleoside towards the product formation; and (ii) to overcome the solubility constraints of araA in aqueous medium, thus providing a new route to the highly productive synthesis of araA-MP.

Magnetic Particles-Based Analytical Platforms for Food Safety Monitoring

Magnetic nanoparticles (MNPs) have attracted growing interest as versatile materials for the development of analytical detection and separation platforms for food safety monitoring. This review discusses recent advances in the synthesis, functionalization and applications of MNPs in bioanalysis. A special emphasis is given to the use of MNPs as an immobilization support for biomolecules and as a target capture and pre-concentration to increase selectivity and sensitivity of analytical platforms for the monitoring of food contaminants. General principles and examples of MNP-based platforms for separation, amplification and detection of analytes of interest in food, including organic and inorganic constituents are discussed.

Estimation of the Effectiveness Factor for Immobilized Enzyme Catalysts through a Simple Conversion Assay

A novel methodology to estimate the effectiveness factor (EF) of an immobilized enzyme catalyst is proposed here. The methodology consists of the determination of the productivity of both the immobilized enzyme catalyst and its corresponding soluble enzyme, plotted as a function of the reaction conversion. The ratio of these productivities corresponds to the EF estimator of the catalyst. Conversion curves were simulated in a batch reactor with immobilized enzyme and soluble enzyme for different values of the S0/KM ratio and Thiele modulus (Φ) to demonstrate this hypothesis. Two different reaction orders were tested: first-order kinetic and Michaelis–Menten-based kinetic with product inhibition. The results showed that the ratio of productivities between the immobilized and soluble enzymes followed the behavior profile presented by the EF with satisfactory agreement. This simple methodology to estimate the EF is based on routine conversion experiments, thus avoiding the exhaustive kinetic and mass transfer characterization of the immobilized enzyme catalyst.

Preparation of immobilized/stabilized biocatalysts of β-glucosidases from different sources: Importance of the support active groups and the immobilization protocol

β-Glucosidases from two different commercial preparations, Pectinex Ultra SP-L and Celluclast® 1.5L, were immobilized on divinylsulfone (DVS) supports at pH 5.0, 7.0, 9.0, and 10. In addition, the biocatalysts were also immobilized in agarose beads activated by glyoxyl, and epoxide as reagent groups. The best immobilization results were observed using higher pH values on DVS-agarose, and for Celluclast® 1.5L, good results were also obtained using the glyoxil-agarose immobilization. The biocatalyst obtained using Pectinex Ultra SP-L showed the highest thermal stability, at 65°C, and an operational stability of 67% of activity after 10 reuses cycles when immobilized on DVS-agarose immobilized at pH 10 and blocked with ethylenediamine. The β-glucosidase from Celluclast® 1.5L produced best results when immobilized on DVS-agarose immobilized at pH 9 and blocked with glycine, reaching 7.76-fold higher thermal stability compared to its free form and maintaining 76% of its activity after 10 successive cycles. The new biocatalysts obtained by these protocols showed reduction of glucose inhibition of enzymes, demonstrating the influence of immobilization protocols, pH, and blocking agent.

Dextran Aldehyde in Biocatalysis: More Than a Mere Immobilization System

Dextran aldehyde (dexOx), resulting from the periodate oxidative cleavage of 1,2-diol moiety inside dextran, is a polymer that is very useful in many areas, including as a macromolecular carrier for drug delivery and other biomedical applications. In particular, it has been widely used for chemical engineering of enzymes, with the aim of designing better biocatalysts that possess improved catalytic properties, making them more stable and/or active for different catalytic reactions. This polymer possesses a very flexible hydrophilic structure, which becomes inert after chemical reduction; therefore, dexOx comes to be highly versatile in a biocatalyst design. This paper presents an overview of the multiple applications of dexOx in applied biocatalysis, e.g., to modulate the adsorption of biomolecules on carrier surfaces in affinity chromatography and biosensors design, to serve as a spacer arm between a ligand and the support in biomacromolecule immobilization procedures or to generate artificial microenvironments around the enzyme molecules or to stabilize multimeric enzymes by intersubunit crosslinking, among many other applications.

Naturally-derived biopolymers: Potential platforms for enzyme immobilization

Naturally-derived biopolymers such as alginate, chitosan, cellulose, agarose, guar gum/guaran, agar, carrageenan, gelatin, dextran, xanthan, and pectins, etc. have appealed significant attention over the past several years owing to their natural abundance and availability all over the years, around the globe. In addition, their versatile properties such as non-toxicity, biocompatibility, biodegradability, flexibility, renewability, and the availability of numerous reactive sites offer significant functionalities with multipurpose applications. At present, intensive research efforts have been focused on engineering enzymes using natural biopolymers as novel support/composite materials for diverse applications in biomedical, environmental, pharmaceutical, food and biofuel/energy sectors. Immobilization appears as a straightforward and promising approach to developing biocatalysts with improved catalytic properties as compared to their free counterparts. Biopolymers-assisted enzymes are more stable, robust, and recoverable than that of free forms, and can be employed for continuous biocatalytic reactions. The present review highlights the recent developments and use of biopolymers and their advanced composites as support carriers for the immobilization of a variety of different enzymes to develop biocatalysts with desired catalytic activity and stability characteristics for emerging applications.

Technological Aspects of the Production of Fructo and Galacto-Oligosaccharides. Enzymatic Synthesis and Hydrolysis

Fructo- and galacto-oligosaccharides (FOS and GOS) are non-digestible oligosaccharides with prebiotic properties that can be incorporated into a wide number of products. This review details the general outlines for the production of FOS and GOS, both by enzymatic synthesis using disaccharides or other substrates, and by hydrolysis of polysaccharides. Special emphasis is laid on technological aspects, raw materials, properties, and applications.

Programmable stimuli-responsive polypeptides for biomimetic synthesis of silica nanocomposites and enzyme self-immobilization

Bioinspired silicification is an attractive route for achieving unique silica nanocomposites. Herein, a novel, facile and inexpensive route for biosilica synthesis is developed using the stimuli-responsive elastin-like polypeptide (ELP). The ELP is precisely tailored to a silica-mineralizing peptide by programming it with lysine residues. The resulting cationic ELP[KV₈F-40] is purified in ultrahigh yield using a chromatography-free ITC purification technique based on thermal-responsive property. Excitingly, the specific activity of ELP is 40-fold higher than that of silaffin. Besides, efficient and strong entrapment of ELP is achieved with over 98% of immobilization yield and less than 2% of leakage. These imply that cationic ELP may be used as a bifunctional tag (purification and immobilization) for fusion protein. An enzyme (xylanase) is therefore chosen to genetically fuse to ELP. The ELP-fused xylanase is purified by ELP with high purity (~98%) and enables the rapid (within minutes) self-immobilization. The immobilization yield was greater than 95%, and the immobilized xylanases hardly leaked from the silica matrix, demonstrating high efficiency of the self-immobilization process. The strategy developed here may provide a new opportunity for fabricating functional silica nanocomposites in a feasible and inexpensive pathway, which will have great potentials in the field of biotechnology.

Cooperativity of covalent attachment and ion exchange on alcalase immobilization using glutaraldehyde chemistry: Enzyme stabilization and improved proteolytic activity

Alcalase was scarcely immobilized on monoaminoethyl-N-aminoethyl (MANAE)-agarose beads at different pH values (<20% at pH 7). The enzyme did not immobilize on MANAE-agarose activated with glutaraldehyde at high ionic strength, suggesting a low reactivity of the enzyme with the support functionalized in this manner. However, the immobilization is relatively rapid when using low ionic strength and glutaraldehyde activated support. Using these conditions, the enzyme was immobilized at pH 5, 7, and 9, and in all cases, the activity vs. Boc-Ala-ONp decreased to around 50%. However, the activity vs. casein greatly depends on the immobilization pH, while at pH 5 it is also 50%, at pH 7 it is around 200%, and at pH 9 it is around 140%. All immobilized enzymes were significantly stabilized compared to the free enzyme when inactivated at pH 5, 7, or 9. The highest stability was always observed when the enzyme was immobilized at pH 9, and the worst stability occurred when the enzyme was immobilized at pH 5, in agreement with the reactivity of the amino groups of the enzyme. Stabilization was lower for the three preparations when the inactivation was performed at pH 5. Thus, this is a practical example on how the cooperative effect of ion exchange and covalent immobilization may be used to immobilize an enzyme when only one independent cause of immobilization is unable to immobilize the enzyme, while adjusting the immobilization pH leads to very different properties of the final immobilized enzyme preparation. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2768, 2019.

One-Step Immobilization and Stabilization of a Recombinant Enterococcus faecium DBFIQ E36 L-Arabinose Isomerase for D-Tagatose Synthesis

A recombinant L-arabinose isomerase from Enterococcus faecium DBFIQ E36 was immobilized onto multifunctional epoxide supports by chemical adsorption and onto a chelate-activated support via polyhistidine-tag, located on the N-terminal (N-His-L-AI) or on the C-terminal (C-His-L-AI) sequence, followed by covalent bonding between the enzyme and the support. The results were compared to reversible L-AI immobilization by adsorption onto charged agarose supports with improved stability. All the derivatives presented immobilization yields of above 75%. The ionic interaction established between agarose gels containing monoaminoethyl-N-aminoethyl structures (MANAE) and the enzyme was the most suitable strategy for L-AI immobilization in comparison to the chelate-activated agarose. In addition, the immobilized biocatalysts by ionic interaction in MANAE showed to be the most stable, retaining up to 100% of enzyme activity for 60 min at 60 °C and with K_m values of 28 and 218 mM for MANAE-N-His-L-AI and MANAE-C-His-L-AI, respectively.

Immobilization and stabilization of alcohol dehydrogenase on polyvinyl alcohol fibre

A polyvinyl alcohol (PVA) fibrous carrier has been chemically modified for the immobilization of yeast alcohol dehydrogenase (ADH) with an aim to increase its stability over a wide pH range, prolong its activity upon storage, and enhance its reusability. The strategy for immobilization involved functionalization of the fibrous carrier with chloropropinoyl chloride followed by amination with ethylenediamine. Tethering of the ADH enzyme to the PVA scaffold was achieved with glutaraldehyde. The activity profile of the immobilized enzyme was compared to soluble enzyme as a function of pH, temperature and reusability. The immobilization of ADH on PVA fibrous carrier shifted the optimal reaction pH from 7 to 9, and improved the thermostability at 60 °C. Furthermore, the immobilized enzyme retained 60% of its original activity after eight cycles of reuse. These results demonstrate that PVA based textiles can serve as a flexible, reusable carrier for enzyme immobilization.

Co-localization of oxidase and catalase inside a porous support to improve the elimination of hydrogen peroxide: Oxidation of biogenic amines by amino oxidase from Pisum sativum

Diamine oxidase (DAO) from Pisum sativum is an enzyme that catalyzes the degradation of biogenic amines (BA) present in wine, producing harmless aldehydes and hydrogen peroxide (H2O2). H2O2 promotes a rapid inactivation of the immobilized enzyme. At first glance, co-immobilization of DAO and catalase (CAT) could improve the elimination of the released hydrogen peroxide. Two different co-immobilized derivatives were prepared: (a) both enzymes co-localized and homogeneously distributed across the whole structure of a porous support, and (b) both enzymes we de-localized inside the porous support: DAO immobilized on the outer part of the porous support and catalase immobilized in the inner part. Co-localized derivatives were seven-fold more effective than de-localized ones for the elimination of hydrogen peroxide inside the porous support. In addition to that, the degradation of putrescine by DAO was three-fold more rapid when using both co-localized enzymes. The optimal co-localized derivative (containing 1.25 mg of DAO plus 25 mg of CAT per g of support) promoted the instantaneous elimination of 91% H2O2 released inside the porous support during putrescine oxidation. This optimal derivative preserves 92% of activity after three reaction cycles and DAO immobilized without catalase only preserves 41% of activity. Co-localization seems to be the key strategy to immobilize two sequential enzymes. When enzymes are immobilized in close proximity to each other in a co-localized pattern, the generation of byproducts as H2O2 is strongly reduced.

Efficient fructose production from plant extracts by immobilized inulinases from Kluyveromyces marxianus and Helianthus tuberosus

The enzymatic hydrolysis of poly- and oligosaccharides from plants seems like an advantageous approach for sugars production. Two inulinases producing fructose from plant oligosaccharides were isolated from yeast Kluyveromyces marxianus and plant Helianthus tuberosus. Both enzymes were immobilized on polymeric carriers by using the static adsorption approach. We could save 80.4% of the initial catalytic activity of plant inulinase immobilized on KU-2 cation-exchange resin and 75.5% of yeast enzyme activity adsorbed on AV-17-2P anion-exchange resin. After immobilization, the Km values increased 1.5 and 6 times for enzymes from K. marxianus and H. tuberosus, respectively. The optimal temperatures for catalysis of both enzymes were increased from 48-50 °C up to 70 °C. The activities of both immobilized enzymes remained unchanged after the 10 cycles of 20-min hydrolysis reaction at 70 °C model batch reactor. Sorbents, native and immobilized enzymes did not exhibit any mutagenic or cytotoxic activity.