The enzyme as drug: application of enzymes as pharmaceuticals

Comprehensive insight into exploring the potential of microbial enzymes in cancer therapy: Progress, challenges, and opportunities: A review

Microbial enzymes are crucial catalysts in various industries due to their versatility and efficiency. The microbial enzymes market has recently expanded due to increased demand for many reasons. Among them are eco-friendly solutions, developing novel microbial strains with enhanced enzymes that perform under harsh conditions, providing sustainability, and raising awareness about the benefits of enzyme-based products. By 2030, the global enzyme market is expected to account for $525 billion, with a growth rate of 6.7 %. L-asparaginase and L-glutaminase are among the leading applied microbial enzymes in antitumor therapy, with a growing market share of 16.5 % and 9.5 %, respectively. The use of microbial enzymes has opened new opportunities to fight various tumors, including leukemia, lymphosarcoma, and breast cancer, which has increased their demand in the pharmaceutical and medicine sectors. Despite their promising applications, commercial use of microbial enzymes faces challenges such as short half-life, immunogenicity, toxicity, and other side effects. Therefore, this review explores the industrial production, purification, formulation, and commercial utilization of microbial enzymes, along with an overview of the global enzyme market. With ongoing discoveries of novel enzymes and their applications, enzyme technology offers promising avenues for cancer treatment and other therapeutic interventions.

Combinatorial therapeutic enzymes to combat multidrug resistance in bacteria

AIMS

Antibiotic resistance including multidrug resistance (MDR) is a negative symbol to the human health system because it loses the capability to treat infections. Unfortunately, the available antibiotics do not show an effective therapeutic response against bacterial infections. In the situation of global antibiotic unresponsiveness, enzymatic therapy especially in combinatorial form seems an effective approach to control bacterial infection and combat resistance. The article is important because it focuses on combinatorial enzymatic therapy that has multiple properties (effective antibacterial performances, antibiofilm capacity, immunomodulators, targeted actions, synergistic actions, multiple targeting, and resistance-proof properties) and can address antibiotic resistance effectively.

MATERIALS AND METHODS

We searched the related topics with Pubmed, Scopus, and Google Scholar databases and finally 73 relevant papers were reviewed in detail and cited in this article.

KEY FINDINGS

Discusses properties of combinatorial therapeutic enzymes made it an accomplished means over antibiotic therapy. This article discusses the need for combinatorial enzymatic therapy against bacterial infection, its distinguished features, and properties with multi-mechanistic antibacterial action. It discussed the European Medicine Agency and Food and Drug Administration-approved therapeutic enzymes (antibacterial and antibiofilm).

SIGNIFICANCE

This article provided the possible combination of the enzyme that may be used as an antibacterial agent along with limitations and future scope of combinatorial antibacterial enzymatic agents. This article could draw the attention of researchers to combinatorial therapeutic enzymatic molecules as effective and futuristic therapy to overcome the problem of multiple antibiotic resistance in bacteria.

Nanosized Complexes of the Proteolytic Enzyme Serratiopeptidase with Cationic Block Copolymer Micelles Enhance the Proliferation and Migration of Human Cells

In this study, we describe the preparation of the cationic block copolymer nanocarriers of the proteolytic enzyme serratiopeptidase (SER). Firstly, an amphiphilic poly(2-(dimethylamino)ethyl methacrylate)-b-poly(ε-caprolactone)-b-poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA9-b-PCL35-b-PDMAEMA9) triblock copolymer was synthesized by reversible addition-fragmentation chain-transfer (RAFT) polymerization. Then, cationic micellar nanocarriers consisting of a PCL hydrophobic core and a PDMAEMA hydrophilic shell were formed by the solvent evaporation method. SER was loaded into the polymeric micelles by electrostatic interaction between the positively charged micellar shell and the negatively charged enzyme molecules. The particle size, zeta potential, and colloid stability of complexes as a function of SER concentration were investigated by dynamic and electrophoretic light scattering. It was found that SER retained its proteolytic activity after immobilization in polymeric carriers. Moreover, the complexes have a concentration-dependent enhancing effect on the proliferation and migration of human keratinocyte HaCaT and gingival fibroblast HGF cells.

Proteases, a powerful biochemical tool in the service of medicine, clinical and pharmaceutical

Proteases, enzymes that hydrolyze peptide bonds, have various applications in medicine, clinical applications, and pharmaceutical development. They are used in cancer treatment, wound debridement, contact lens cleaning, prion degradation, biofilm removal, and fibrinolytic agents. Proteases are also crucial in cardiovascular disease treatment, emphasizing the need for safe, affordable, and effective fibrinolytic drugs. Proteolytic enzymes and protease biosensors are increasingly used in diagnostic and therapeutic applications. Advanced technologies, such as nanomaterials-based sensors, are being developed to enhance the sensitivity, specificity, and versatility of protease biosensors. These biosensors are becoming effective tools for disease detection due to their precision and rapidity. They can detect extracellular and intracellular proteases, as well as fluorescence-based methods for real-time and label-free detection of virus-related proteases. The active utilization of proteolytic enzymatic biosensors is expected to expand significantly in biomedical research, in-vitro model systems, and drug development. We focused on journal articles and books published in English between 1982 and 2024 for this study.

Purification and partial physical-chemical characterization of a new bovine trypsin proteoform (zeta-trypsin)

Recent advancements in enzyme research have unveiled a new proteoform of bovine trypsin, expanding our understanding of this well-characterized enzyme. While generally similar to other trypsins, this novel proteoform comprises three polypeptide chains, marking a significant difference in activity, kinetic properties, and conformational stability. Compared with the already known bovine trypsin proteoforms, the results showed a lower: activity, kcat and kcat.KM-1 and protein 'foldedness' ratio for the new proteoform. Molecular autolysis, a common feature in trypsin and chymotrypsin, has been explored through comparative physical chemistry properties with other proteoforms. This new proteoform of trypsin not only enriches the existing enzyme repertoire but also promises to shed light on the intricate physiological pathway for enzyme inactivation. Our results suggest that the new trypsin proteoform is one of the likely final pathways for enzyme inactivation in a physiological environment. This discovery opens up new avenues for further research into the functional implications of this new trypsin proteoform.

A review on L-methioninase in cancer therapy: Precision targeting, advancements and diverse applications for a promising future

Cancer remains a global health challenge, demanding novel therapeutic options due to the debilitating side effects of conventional treatments on healthy tissues. The review highlights the potential of L-methioninase, a pyridoxal-5-phosphate (PLP)-dependent enzyme, as a promising avenue in alternative cancer therapy. L-methioninase offers a unique advantage, its ability to selectively target and inhibit the growth of cancer cells without harming healthy cells. This selectivity arises because tumor cells lack an essential enzyme called methionine synthase, which healthy cells use to make the vital amino acid L-methionine. Several sources harbor L-methioninase, including bacteria, fungi, plants, and protozoa. Future research efforts can explore and exploit this diverse range of sources to improve the therapeutic potential of L-methioninase in the fight against cancer. Despite challenges, research actively explores microbial L-methioninase for its anticancer potential. This review examines the enzyme's side effects, advancements in combination therapies, recombinant technologies, polymer conjugation and novel delivery methods like nanoparticles, while highlighting the success of oral administration in preclinical trials. Beyond its promising role in cancer therapy, L-methioninase holds potential applications in food science, antioxidants, and various health concerns like diabetes, cardiovascular issues, and neurodegenerative diseases. This review provides a piece of current knowledge and future prospects of L-methioninase, exploring its diverse therapeutic potential.

An up-to-date review of biomedical applications of serratiopeptidase and its biobetter derivatives as a multi-potential metalloprotease

Serratiopeptidase is a bacterial metalloprotease used in a variety of medical applications. The multidimensional properties of serratiopeptidase make it noticeable as a miraculous enzyme. Anti-coagulant, anti-inflammatory and anti-biofilm activity of serratiopeptidase making it useful in reducing pain and swelling associated with various conditions including arthritis, diabetes, cancer, swelling, pain and also thrombolytic disorders. It breaks down fibrin, thins the fluids formed during inflammation and due to its anti-biofilm activity, can be used in the combination of antibiotics to reduce development of antibiotic resistance. However, some drawbacks like sensitivity to environmental conditions and low penetration into cells due to its large size have limited its usage as a potent pharmaceutical agent. To overcome such limitations, improved versions of the enzyme were introduced using protein engineering in our previous studies. Novel functional serratiopeptidases with shorter length and higher stability have seemingly created a hope for using this enzyme as a more effective therapeutic enzyme. This review explains the structural properties and functional aspects of serratiopeptidase, its main characteristics and properties, pre-clinical and clinical applications of the enzyme, improved qualities of the modified forms, different formulations of the enzyme, and the potential future developments.

Treatment-induced and Pre-existing Anti-peg Antibodies: Prevalence, Clinical Implications, and Future Perspectives

Polyethylene glycol (PEG) is a versatile polymer that is used in numerous pharmaceutical applications like the food industry, a wide range of disinfectants, cosmetics, and many commonly used household products. PEGylation is the term used to describe the covalent attachment of PEG molecules to nanocarriers, proteins and peptides, and it is used to prolong the circulation half-life of the PEGylated products. Consequently, PEGylation improves the efficacy of PEGylated therapeutics. However, after four decades of research and more than two decades of clinical applications, an unappealing side of PEGylation has emerged. PEG immunogenicity and antigenicity are remarkable challenges that confound the widespread clinical application of PEGylated therapeutics - even those under clinical trials - as anti-PEG antibodies (Abs) are commonly reported following the systemic administration of PEGylated therapeutics. Furthermore, pre-existing anti-PEG Abs have also been reported in healthy individuals who have never been treated with PEGylated therapeutics. The circulating anti-PEG Abs, both treatment-induced and pre-existing, selectively bind to PEG molecules of the administered PEGylated therapeutics inducing activation of the complement system, which results in remarkable clinical implications with varying severity. These include increased blood clearance of the administered PEGylated therapeutics through what is known as the accelerated blood clearance (ABC) phenomenon and initiation of serious adverse effects through complement activation-related pseudoallergic reactions (CARPA). Therefore, the US FDA industry guidelines have recommended the screening of anti-PEG Abs, in addition to Abs against PEGylated proteins, in the clinical trials of PEGylated protein therapeutics. In addition, strategies revoking the immunogenic response against PEGylated therapeutics without compromising their therapeutic efficacy are important for the further development of advanced PEGylated therapeutics and drug-delivery systems.

Bringing enzymes to the proximity party

Enzymes are used to treat a wide variety of human diseases, including lysosomal storage disorders, clotting disorders, and cancers. While enzyme therapeutics catalyze highly specific reactions, they often suffer from a lack of cellular or tissue selectivity. Targeting an enzyme to specific disease-driving cells and tissues can mitigate off-target toxicities and provide novel therapeutic avenues to treat otherwise intractable diseases. Targeted enzymes have been used to treat cancer, in which the enzyme is either carefully selected or engineered to reduce on-target off-tumor toxicity, or to treat lysosomal storage disorders in cell types that are not addressed by standard enzyme replacement therapies. In this review, we discuss the different targeted enzyme modalities and comment on the future of these approaches.

Engineering of Therapeutic and Detoxifying Enzymes

Therapeutic enzymes present excellent opportunities for the treatment of human disease, modulation of metabolic pathways and system detoxification. However, current use of enzyme therapy in the clinic is limited as naturally occurring enzymes are seldom optimal for such applications and require substantial improvement by protein engineering. Engineering strategies such as design and directed evolution that have been successfully implemented for industrial biocatalysis can significantly advance the field of therapeutic enzymes, leading to biocatalysts with new-to-nature therapeutic activities, high selectivity, and suitability for medical applications. This minireview highlights case studies of how state-of-the-art and emerging methods in protein engineering are explored for the generation of therapeutic enzymes and discusses gaps and future opportunities in the field of enzyme therapy.

Recent advances in glucose oxidase-based nanocarriers for tumor targeting therapy

Glucose oxidase (GOx) can specifically catalyze the conversion of β-d-glucose into gluconic acid and hydrogen peroxide (H2O2) in the presence of oxygen, making it promising for tumor starvation therapy and oxidative therapy. However, GOx's immunogenicity, poor in vivo stability, short half-life, and potential systemic toxicity, limit its application in cancer therapy. Nanocarriers are capable of improving the pharmacological properties of therapeutic drugs (e.g. stability, circulating half-life, and tumor accumulation) and lower toxicity, hence resolving GOx issues and enhancing its efficacy. Although the application of targeted nanocarriers based on GOx has recently flourished, this field has not yet been reviewed and evaluated. Herein, we initially examined the mechanism of GOx-based nanocarriers for enhanced tumor therapy. Also, we present a comprehensive and up-to-date review that highlights GOx-based nanocarriers for tumor targeting therapy. This review expands on GOx-based nano-targeted combination therapies from both passive and active targeting perspectives, meanwhile, active targeting is further classified into ligand-mediated targeting and physical-mediated targeting. Furthermore, this review also emphasizes the present challenges and promising advancements.

Alginate-based materials for enzyme encapsulation

Enzymes are widely used in industry due to their high efficiency and selectivity. However, their low stability during certain industrial processes can result in a significant loss of catalytic activity. Encapsulation is a promising technique that can stabilize enzymes by protecting them from environmental stresses such as extreme temperature and pH, mechanical force, organic solvents, and proteases. Alginate and alginate-based materials have emerged as effective carriers for enzyme encapsulation due to their biocompatibility, biodegradability, and ability to form gel beads through ionic gelation. This review presents various alginate-based encapsulation systems for enzyme stabilization and explores their applications in different industries. We discuss the preparation methods of alginate encapsulated enzymes and analyze the release mechanisms of enzymes from alginate materials. Additionally, we summarize the characterization techniques used for enzyme-alginate composites. This review provides insights into the use of alginate encapsulation as a means of stabilizing enzymes and highlights the potential benefits for various industrial applications.

Recent Progress of Rational Modified Nanocarriers for Cytosolic Protein Delivery

Therapeutic proteins garnered significant attention in the field of disease treatment. In comparison to small molecule drugs, protein therapies offer distinct advantages, including high potency, specificity, low toxicity, and reduced carcinogenicity, even at minimal concentrations. However, the full potential of protein therapy is limited by inherent challenges such as large molecular size, delicate tertiary structure, and poor membrane penetration, resulting in inefficient intracellular delivery into target cells. To address these challenges and enhance the clinical applications of protein therapies, various protein-loaded nanocarriers with tailored modifications were developed, including liposomes, exosomes, polymeric nanoparticles, and nanomotors. Despite these advancements, many of these strategies encounter significant issues such as entrapment within endosomes, leading to low therapeutic efficiency. In this review, we extensively discussed diverse strategies for the rational design of nanocarriers, aiming to overcome these limitations. Additionally, we presented a forward-looking viewpoint on the innovative generation of delivery systems specifically tailored for protein-based therapies. Our intention was to offer theoretical and technical support for the development and enhancement of nanocarriers capable of facilitating cytosolic protein delivery.

Marine enzymes: Classification and application in various industries

Oceans are regarded as a plentiful and sustainable source of biological compounds. Enzymes are a group of marine biomaterials that have recently drawn more attention because they are produced in harsh environmental conditions such as high salinity, extensive pH, a wide temperature range, and high pressure. Hence, marine-derived enzymes are capable of exhibiting remarkable properties due to their unique composition. In this review, we overviewed and discussed characteristics of marine enzymes as well as the sources of marine enzymes, ranging from primitive organisms to vertebrates, and presented the importance, advantages, and challenges of using marine enzymes with a summary of their applications in a variety of industries. Current biotechnological advancements need the study of novel marine enzymes that could be applied in a variety of ways. Resources of marine enzyme can benefit greatly for biotechnological applications duo to their biocompatible, ecofriendly and high effectiveness. It is beneficial to use the unique characteristics offered by marine enzymes to either develop new processes and products or improve existing ones. As a result, marine-derived enzymes have promising potential and are an excellent candidate for a variety of biotechnology applications and a future rise in the use of marine enzymes is to be anticipated.

The design of small-molecule prodrugs and activatable phototherapeutics for cancer therapy

Cancer remains as one of the most significant health problems, with approximately 19 million people diagnosed worldwide each year. Chemotherapy is a routinely used method to treat cancer patients. However, current treatment options lack the appropriate selectivity for cancer cells, are prone to resistance mechanisms, and are plagued with dose-limiting toxicities. As such, researchers have devoted their attention to developing prodrug-based strategies that have the potential to overcome these limitations. This tutorial review highlights recently developed prodrug strategies for cancer therapy. Prodrug examples that provide an integrated diagnostic (fluorescent, photoacoustic, and magnetic resonance imaging) response, which are referred to as theranostics, are also discussed. Owing to the non-invasive nature of light (and X-rays), we have discussed external excitation prodrug strategies as well as examples of activatable photosensitizers that enhance the precision of photodynamic therapy/photothermal therapy. Activatable photosensitizers/photothermal agents can be seen as analogous to prodrugs, with their phototherapeutic properties at a specific wavelength activated in the presence of disease-related biomarkers. We discuss each design strategy and illustrate the importance of targeting biomarkers specific to the tumour microenvironment and biomarkers that are known to be overexpressed within cancer cells. Moreover, we discuss the advantages of each approach and highlight their inherent limitations. We hope in doing so, the reader will appreciate the current challenges and available opportunities in the field and inspire subsequent generations to pursue this crucial area of cancer research.

Portable Alkaline Phosphatase-Hydrogel Platform: From Enzyme Characterization to Phosphate Sensing

Here, we present a study on the incorporation and characterization of the enzyme alkaline phosphatase (ALP) into a three-dimensional polymeric network through a green protocol to obtain transparent hydrogels (ALP@AETA) that can be stored at room temperature and potentially used as a disposable biosensor platform for the rapid detection of ALP inhibitors. For this purpose, different strategies for the immobilization of ALP in the hydrogel were examined and the properties of the new material, compared to the hydrogel in the absence of enzyme, were studied. The conformation and stability of the immobilized enzyme were characterized by monitoring the changes in its intrinsic fluorescence as a function of temperature, in order to study the unfolding/folding process inside the hydrogel, inherently related to the enzyme activity. The results show that the immobilized enzyme retains its activity, slightly increases its thermal stability and can be stored as a xerogel at room temperature without losing its properties. A small portion of a few millimeters of ALP@AETA xerogel was sufficient to perform enzymatic activity inhibition assays, so as a proof of concept, the device was tested as a portable optical biosensor for the detection of phosphate in water with satisfactory results. Given the good stability of the ALP@AETA xerogel and the interesting applications of ALP, not only in the environmental field but also as a therapeutic enzyme, we believe that this study could be of great use for the development of new devices for sensing and protein delivery.

Engineering of a T7 Bacteriophage Endolysin Variant with Enhanced Amidase Activity

The therapeutic use of bacteriophage-encoded endolysins as enzybiotics has increased significantly in recent years due to the emergence of antibiotic resistant bacteria. Phage endolysins lyse the bacteria by targeting their cell wall. Various engineering strategies are commonly used to modulate or enhance the utility of therapeutic enzymes. This study employed a structure-guided mutagenesis approach to engineer a T7 bacteriophage endolysin (T7L) with enhanced amidase activity and lysis potency via replacement of a noncatalytic gating residue (His 37). Two H37 variants (H37A and H37K) were designed and characterized comprehensively using integrated biophysical and biochemical techniques to provide mechanistic insights into their structure-stability-dynamics-activity paradigms. Among the studied proteins, cell lysis data suggested that the obtained H37A variant exhibits amidase activity (∼35%) enhanced compared to that of wild-type T7 endolysin (T7L-WT). In contrast to this, the H37K variant is highly unstable, prone to aggregation, and less active. Comparison of the structure and dynamics of the H37A variant to those of T7L-WT evidenced that the alteration at the site of H37 resulted in long-range structural perturbations, attenuated the conformational heterogeneity, and quenched the microsecond to millisecond time scale motions. Stability analysis confirmed the altered stability of H37A compared to that of its WT counterpart. All of the obtained results established that the H37A variant enhances the lysis activity by regulating the stability-activity trade-off. This study provided deeper atomic level insights into the structure-function relationships of endolysin proteins, thus aiding researchers in the rational design of engineered endolysins with enhanced therapeutic properties.

Supramolecular enzyme-mimicking catalysts self-assembled from peptides

Natural enzymes catalyze biochemical transformations in superior catalytic efficiency and remarkable substrate specificity. The excellent catalytic repertoire of enzymes is attributed to the sophisticated chemical structures of their active sites, as a result of billions-of-years natural evolution. However, large-scale practical applications of natural enzymes are restricted due to their poor stability, difficulty in modification, and high costs of production. One viable solution is to fabricate supramolecular catalysts with enzyme-mimetic active sites. In this review, we introduce the principles and strategies of designing peptide-based artificial enzymes which display catalytic activities similar to those of natural enzymes, such as aldolases, laccases, peroxidases, and hydrolases (mainly the esterases and phosphatases). We also discuss some multifunctional enzyme-mimicking systems which are capable of catalyzing orthogonal or cascade reactions. We highlight the relationship between structures of enzyme-like active sites and the catalytic properties, as well as the significance of these studies from an evolutionary point of view.

Replacement of Trypsin by Proteases for Medical Applications

Background

Cell culture has a crucial role in many applications in biotechnology. The production of vaccines, recombinant proteins, tissue engineering, and stem cell therapy all need cell culture. Most of these activities needed adherent cells to move, which should be trypsinized several times until received on a large scale. Although trypsin is manufactured from the bovine or porcine pancreas, the problem of contamination by unwanted animal proteins, unwanted immune reactions, or contamination to pathogen reagents is the main problem.

Objectives

This study investigated microbial proteases as a safe alternative for trypsin replacement in cell culture experiments for the detachment of adherent cells.

Methods

The bacteria were isolated from the leather industry effluent based on their protease enzymes. After sequencing their 16S ribosomal deoxyribonucleic acid, their protease enzymes were purified, and their enzyme activities were assayed. The alteration of enzymatic activities using different substrates and the effect of substrate concentrations on enzyme activities were determined. The purified proteases were evaluated for cell detachment in the L929 fibroblast cells compared to trypsin. The separated cells were cultured again, and cell proliferation was determined by the MTT assay.

Results

The results showed that the isolated bacteria were Bacillus pumilus, Stenotrophomonas sp., Klebsiella aerogenes, Stenotrophomonas maltophilia, and Bacillus licheniformis. Among the isolated bacteria, the highest and the lowest protease activity belonged to Stenotrophomonas sp. and K. aerogenes, with 60.34 and 11.09 U/mL protease activity, respectively. All the isolated microbial proteases successfully affected L929 fibroblast cells' surface proteins and detached the cells. A significant induction in cell proliferation was observed in the cells treated with K. aerogenes protease and B. pumilus protease, respectively (P < 0.05).

Conclusions

The obtained results suggested that microbial proteases can be used as safe and efficient alternatives to trypsin in cell culture in biopharmaceutical applications.

Effects of Sequence Features on Machine-Learned Enzyme Classification Fidelity

Assigning enzyme commission (EC) numbers using sequence information alone has been the subject of recent classification algorithms where statistics, homology and machine-learning based methods are used. This work benchmarks performance of a few of these algorithms as a function of sequence features such as chain length and amino acid composition (AAC). This enables determination of optimal classification windows for de novo sequence generation and enzyme design. In this work we developed a parallelization workflow which efficiently processes >500,000 annotated sequences through each candidate algorithm and a visualization workflow to observe the performance of the classifier over changing enzyme length, main EC class and AAC. We applied these workflows to the entire SwissProt database to date (n = 565245) using two, locally installable classifiers, ECpred and DeepEC, and collecting results from two other webserver-based tools, Deepre and BENZ-ws. It is observed that all the classifiers exhibit peak performance in the range of 300 to 500 amino acids in length. In terms of main EC class, classifiers were most accurate at predicting translocases (EC-6) and were least accurate in determining hydrolases (EC-3) and oxidoreductases (EC-1). We also identified AAC ranges that are most common in the annotated enzymes and found that all classifiers work best in this common range. Among the four classifiers, ECpred showed the best consistency in changing feature space. These workflows can be used to benchmark new algorithms as they are developed and find optimum design spaces for the generation of new, synthetic enzymes.

Current advances and research prospects for agricultural and industrial uses of microbial strains available in world collections

Microorganisms are an important component of the ecosystem and have an enormous impact on human lives. Moreover, microorganisms are considered to have desirable effects on other co-existing species in a variety of habitats, such as agriculture and industries. In this way, they also have enormous environmental applications. Hence, collections of microorganisms with specific traits are a crucial step in developing new technologies to harness the microbial potential. Microbial culture collections (MCCs) are a repository for the preservation of a large variety of microbial species distributed throughout the world. In this context, culture collections (CCs) and microbial biological resource centres (mBRCs) are vital for the safeguarding and circulation of biological resources, as well as for the progress of the life sciences. Ex situ conservation of microorganisms tagged with specific traits in the collections is the crucial step in developing new technologies to harness their potential. Type strains are mainly used in taxonomic study, whereas reference strains are used for agricultural, biotechnological, pharmaceutical research and commercial work. Despite the tremendous potential in microbiological research, little effort has been made in the true sense to harness the potential of conserved microorganisms. This review highlights (1) the importance of available global microbial collections for man and (2) the use of these resources in different research and applications in agriculture, biotechnology, and industry. In addition, an extensive literature survey was carried out on preserved microorganisms from different collection centres using the Web of Science (WoS) and SCOPUS. This review also emphasizes knowledge gaps and future perspectives. Finally, this study provides a critical analysis of the current and future roles of microorganisms available in culture collections for different sustainable agricultural and industrial applications. This work highlights target-specific potential microbial strains that have multiple important metabolic and genetic traits for future research and use.

Polyethylene glycol (PEG): The nature, immunogenicity, and role in the hypersensitivity of PEGylated products

Polyethylene glycol (PEG) is a versatile polymer that is widely used as an additive in foods and cosmetics, and as a carrier in PEGylated therapeutics. Even though PEG is thought to be less immunogenic, or perhaps even non-immunogenic, with a variety of physicochemical properties, there is mounting evidence that PEG causes immunogenic responses when conjugated with other materials such as proteins and nanocarriers. Under these conditions, PEG with other materials can result in the production of anti-PEG antibodies after administration. The antibodies that are induced seem to have a deleterious impact on the therapeutic efficacy of subsequently administered PEGylated formulations. In addition, hypersensitivity to PEGylated formulations could be a significant barrier to the utility of PEGylated products. Several reports have linked the presence of anti-PEG antibodies to incidences of complement activation-related pseudoallergy (CARPA) following the administration of PEGylated formulations. The use of COVID-19 mRNA vaccines, which are composed mainly of PEGylated lipid nanoparticles (LNPs), has recently gained wide acceptance, although many cases of post-vaccination hypersensitivity have been documented. Therefore, our review focuses not only on the importance of PEGs and its great role in improving the therapeutic efficacy of various medications, but also on the hypersensitivity reactions attributed to the use of PEGylated products that include PEG-based mRNA COVID-19 vaccines.

Enzyme activity engineering based on sequence co-evolution analysis

The utility of engineering enzyme activity is expanding with the development of biotechnology. Conventional methods have limited applicability as they require high-throughput screening or three-dimensional structures to direct target residues of activity control. An alternative method uses sequence evolution of natural selection. A repertoire of mutations was selected for fine-tuning enzyme activities to adapt to varying environments during the evolution. Here, we devised a strategy called sequence co-evolutionary analysis to control the efficiency of enzyme reactions (SCANEER), which scans the evolution of protein sequences and direct mutation strategy to improve enzyme activity. We hypothesized that amino acid pairs for various enzyme activity were encoded in the evolutionary history of protein sequences, whereas loss-of-function mutations were avoided since those are depleted during the evolution. SCANEER successfully predicted the enzyme activities of beta-lactamase and aminoglycoside 3'-phosphotransferase. SCANEER was further experimentally validated to control the activities of three different enzymes of great interest in chemical production: cis-aconitate decarboxylase, α-ketoglutaric semialdehyde dehydrogenase, and inositol oxygenase. Activity-enhancing mutations that improve substrate-binding affinity or turnover rate were found at sites distal from known active sites or ligand-binding pockets. We provide SCANEER to control desired enzyme activity through a user-friendly webserver.

Recombinant production and characterization of L-glutaminase (glsA) as a promiscuity therapeutic enzyme

Because of the therapeutical impacts of hydrolytic enzymes in different diseases, in particular malignancies, we aimed to produce a recombinant putative L-glutaminase (GLS A_SL-1) from a recently characterized halo-thermotolerant Bacillus sp. SL-1. For this purpose, the glsA gene was identified and efficiently overexpressed in the Origami™ B (DE3) strain. The yield of the purified GLS A_SL-1 was ~ 20 mg/L, indicating a significant expression of recombinant enzyme in the Origami. The enzyme activity assay revealed a significant hydrolytic effect of the recombinant GLS A_SL-1 on L-asparagine (Asn) (i.e., K_m 39.8 μM, k_cat 19.9 S^-1) with a minimal affinity for L-glutamine (Gln). The GLS A_SL-1 significantly suppressed the growth of leukemic Jurkat cells through apoptosis induction (47.5%) in the IC₅₀ dosage of the enzyme. The GLS A_SL-1 could also change the Bax/Bcl2 expression ratio, indicating its apoptotic effect on cancer cells. The in silico analysis was conducted to predict structural features related to the histidine-tag exposure in the N- or C-terminal of the recombinant GLS A_SL-1. In addition, molecular docking simulation for substrate specificity revealed a greater binding affinity of Asn to the enzyme binding-site residues than Gln, which was confirmed in experimental procedures as well. In conclusion, the current study introduced a recombinant GLS A_SL-1 with unique functional and structural features, highlighting its potential pharmaceutical and medical importance. GLS A_SL-1 represents the first annotated enzyme from Bacillus with prominent asparaginase activity, which can be considered for developing alternative enzymes in therapeutic applications. KEY POINTS: • Hydrolytic enzymes have critical applications in different types of human malignancies. • A recombinant L-glutaminase (GLS A_SL-1) was produced from halo-thermotolerant Bacillus sp. SL-1. • GLS A_SL-1 displayed a marked hydrolytic activity on L-asparagine compared to the L-glutamine. • GLS A_SL-1 with significant substrate promiscuity may be an alternative for developing novel pharmaceuticals.

Combining a Genetically Engineered Oxidase with Hydrogen-Bonded Organic Frameworks (HOFs) for Highly Efficient Biocomposites

Enzymes incorporated into hydrogen-bonded organic frameworks (HOFs) via bottom-up synthesis are promising biocomposites for applications in catalysis and sensing. Here, we explored synthetic incorporation of d-amino acid oxidase (DAAO) with the metal-free tetraamidine/tetracarboxylate-based BioHOF-1 in water. N-terminal enzyme fusion with the positively charged module Zbasic2 strongly boosted the loading (2.5-fold; ≈500 mg enzyme gmaterial-1 ) and the specific activity (6.5-fold; 23 U mg-1 ). The DAAO@BioHOF-1 composites showed superior activity with respect to every reported carrier for the same enzyme and excellent stability during catalyst recycling. Further, extension to other enzymes, including cytochrome P450 BM3 (used in the production of high-value oxyfunctionalized compounds), points to the versatility of genetic engineering as a strategy for the preparation of biohybrid systems with unprecedented properties.

Liposomes as Tools to Improve Therapeutic Enzyme Performance

The drugs concept has changed during the last few decades, meaning the acceptance of not only low molecular weight entities but also macromolecules as bioagent constituents of pharmaceutics. This has opened a new era for a different class of molecules, namely proteins in general and enzymes in particular. The use of enzymes as therapeutics has posed new challenges in terms of delivery and the need for appropriate carrier systems. In this review, we will focus on enzymes with therapeutic properties and their applications, listing some that reached the pharmaceutical market. Problems associated with their clinical use and nanotechnological strategies to solve some of their drawbacks (i.e., immunogenic reactions and low circulation time) will be addressed. Drug delivery systems will be discussed, with special attention being paid to liposomes, the most well-studied and suitable nanosystem for enzyme delivery in vivo. Examples of liposomal enzymatic formulations under development will be described and successful pre-clinical results of two enzymes, L-Asparaginase and Superoxide dismutase, following their association with liposomes will be extensively discussed.

Industrial applications of immobilized nano-biocatalysts

Immobilized enzyme-based catalytic constructs could greatly improve various industrial processes due to their extraordinary catalytic activity and reaction specificity. In recent decades, nano-enzymes, defined as enzyme immobilized on nanomaterials, gained popularity for the enzymes' improved stability, reusability, and ease of separation from the biocatalytic process. Thus, enzymes can be strategically incorporated into nanostructured materials to engineer nano-enzymes, such as nanoporous particles, nanofibers, nanoflowers, nanogels, nanomembranes, metal-organic frameworks, multi-walled or single-walled carbon nanotubes, and nanoparticles with tuned shape and size. Surface-area-to-volume ratio, pore-volume, chemical compositions, electrical charge or conductivity of nanomaterials, protein charge, hydrophobicity, and amino acid composition on protein surface play fundamental roles in the nano-enzyme preparation and catalytic properties. With proper understanding, the optimization of the above-mentioned factors will lead to favorable micro-environments for biocatalysts of industrial relevance. Thus, the application of nano-enzymes promise to further strengthen the advances in catalysis, biotransformation, biosensing, and biomarker discovery. Herein, this review article spotlights recent progress in nano-enzyme development and their possible implementation in different areas, including biomedicine, biosensors, bioremediation of industrial pollutants, biofuel production, textile, leather, detergent, food industries and antifouling.

Immobilization of β-Galactosidase by Encapsulation of Enzyme-Conjugated Polymer Nanoparticles Inside Hydrogel Microparticles

Increasing the shelf life of enzymes and making them reusable is a prominent topic in biotechnology. The encapsulation inside hydrogel microparticles (HMPs) can enhance the enzyme's stability by preserving its native conformation and facilitating continuous biocatalytic processes and enzyme recovery. In this study, we present a method to immobilize β-galactosidase by, first, conjugating the enzyme onto the surface of polymer nanoparticles, and then encapsulating these enzyme-conjugated nanoparticles (ENPs) inside HMPs using microfluidic device paired with UV-LEDs. Polymer nanoparticles act as anchors for enzyme molecules, potentially preventing their leaching through the hydrogel network especially during swelling. The affinity binding (through streptavidin-biotin interaction) was used as an immobilization technique of β-galactosidase on the surface of polymer nanoparticles. The hydrogel microparticles of roughly 400 μm in size (swollen state) containing unbound enzyme and ENPs were produced. The effects of encapsulation and storage in different conditions were evaluated. It was discovered that the encapsulation in acrylamide (AcAm) microparticles caused an almost complete loss of enzymatic activity. Encapsulation in poly(ethylene glycol) (PEG)-diacrylate microparticles, on the other hand, showed a residual activity of 15-25%, presumably due to a protective effect of PEG during polymerization. One of the major factors that affected the enzyme activity was presence of photoinitiator exposed to UV-irradiation. Storage studies were carried out at room temperature, in the fridge and in the freezer throughout 1, 7 and 28 days. The polymer nanoparticles showcased excellent immobilization properties and preserved the activity of the conjugated enzyme at room temperature (115% residual activity after 28 days), while a slight decrease was observed for the unbound enzyme (94% after 28 days). Similar trends were observed for encapsulated ENPs and unbound enzyme. Nevertheless, storage at -26°C resulted in an almost complete loss of enzymatic activity for all samples.

L-asparaginase mediated therapy in L-asparagine auxotrophic cancers: A review

Microbial L-asparaginase is the most effective first-line therapeutic used in the treatment protocols of paediatric and adult leukemia. Leukemic cell's auxotrophy for L-asparagine is exploited as a therapeutic strategy to mediate cell death through metabolic blockade of L-asparagine using L-asparaginase. Escherichia coli and Erwinia chrysanthemi serve as the major enzyme deriving sources accepted in clinical practise and the enzyme has bestowed improvements in patient outcomes over the last 40 years. However, an array of side effects generated by the native enzymes due to glutamine co-catalysis and short serum stays augmenting frequent dosages, intended a therapeutic switch towards the development of biobetter alternatives for the enzyme including the formulations resulting in sustained local depletion of L-asparagine. In addition, the treatment with L-asparaginase in few cancer types has proven to elicit drug-induced cytoprotective autophagy mechanisms and therefore warrants concern. Although the off-target glutamine hydrolysis has been viewed in contributing the drug-induced secondary responses in cells deficient with asparagine synthetase machinery, the beneficial role of glutaminase-asparaginase in proliferative regulation of asparagine prototrophic cells has been looked forward. The current review provides an overview on the enzyme's clinical applications in leukemia and possible therapeutic implications in other solid tumours, recent advancements in drug formulations, and discusses the aspects of two-sided roles of glutaminase-asparaginases and drug-induced cytoprotective autophagy mechanisms.

Multifunctionality of Nanosized Calcium Apatite Dual-Doped with Li+/Eu3+ Ions Related to Cell Culture Studies and Cytotoxicity Evaluation In Vitro

Li⁺/Eu³⁺ dual-doped calcium apatite analogues were fabricated using a microwave stimulated hydrothermal technique. XRPD, FT-IR, micro-Raman spectroscopy, TEM and SAED measurements indicated that obtained apatites are single-phased, crystallize with a hexagonal structure, have similar morphology and nanometric size as well as show red luminescence. Lithium effectively modifies the local symmetry of optical active sites and, thus, affects the emission efficiency. Moreover, the hydrodynamic size and surface charge of the nanoparticles have been extensively studied. The protein adsorption (lysozyme, LSZ; bovine serum albumin, BSA) on the nanoparticle surface depended on the type of cationic dopant (Li⁺, Eu³⁺) and anionic group (OH⁻, Cl⁻, F⁻) of the apatite matrix. Interaction with LSZ resulted in a positive zeta potential, and the nanoparticles had the lowest hydrodynamic size in this protein medium. The cytotoxicity assessment was carried out on the human osteosarcoma cell line (U2OS), murine macrophages (J774.E), as well as human red blood cells (RBCs). The studied apatites were not cytotoxic to RBCs and J774.E cells; however, at higher concentrations of nanoparticles, cytotoxicity was observed against the U2OS cell line. No antimicrobial activity was detected against Gram-negative bacteria with one exception for P. aeruginosa treated with Li⁺-doped fluorapatite.

Bottlebrush Polymer-Conjugated Melittin Exhibits Enhanced Antitumor Activity and Better Safety Profile

Despite potency against a variety of cancers in preclinical systems, melittin (MEL), a major peptide in bee venom, exhibits non-specific toxicity, severe hemolytic activity, and poor pharmacological properties. Therefore, its advancement in the clinical translation system has been limited to early-stage trials. Herein, we report a biohybrid involving a bottlebrush-architectured poly(ethylene glycol) (PEG) and MEL. Termed pacMEL, the conjugate consists of a high-density PEG arrangement, which provides MEL with steric inhibition against protein access, while the high molecular weight of pacMEL substantially enhances plasma pharmacokinetics with a ∼10-fold increase in the area under the curve (AUC∞) compared to free MEL. pacMEL also significantly reduces hepatic damage and unwanted innate immune response and all but eliminated hemolytic activities of MEL. Importantly, pacMEL passively accumulates at subcutaneously inoculated tumor sites and exhibits stronger tumor-suppressive activity than molecular MEL. Collectively, pacMEL makes MEL a safer and more appealing drug candidate.

Enzyme Therapy: Current Challenges and Future Perspectives

In recent years, enzymes have risen as promising therapeutic tools for different pathologies, from metabolic deficiencies, such as fibrosis conditions, ocular pathologies or joint problems, to cancer or cardiovascular diseases. Treatments based on the catalytic activity of enzymes are able to convert a wide range of target molecules to restore the correct physiological metabolism. These treatments present several advantages compared to established therapeutic approaches thanks to their affinity and specificity properties. However, enzymes present some challenges, such as short in vivo half-life, lack of targeted action and, in particular, patient immune system reaction against the enzyme. For this reason, it is important to monitor serum immune response during treatment. This can be achieved by conventional techniques (ELISA) but also by new promising tools such as microarrays. These assays have gained popularity due to their high-throughput analysis capacity, their simplicity, and their potential to monitor the immune response of patients during enzyme therapies. In this growing field, research is still ongoing to solve current health problems such as COVID-19. Currently, promising therapeutic alternatives using the angiotensin-converting enzyme 2 (ACE2) are being studied to treat COVID-19.

Arginine depriving enzymes: applications as emerging therapeutics in cancer treatment

Cancer is the second leading cause of death globally. Chemotherapy and radiation therapy and other medications are employed to treat various types of cancer. However, each treatment has its own set of side effects, owing to its low specificity. As a result, there is an urgent need for newer therapeutics that do not disrupt healthy cells' normal functioning. Depriving nutrient or non/semi-essential amino acids to which cancerous cells are auxotrophic remains one such promising anticancer strategy. L-Arginine (Arg) is a semi-essential vital amino acid involved in versatile metabolic processes, signaling pathways, and cancer cell proliferation. Hence, the administration of Arg depriving enzymes (ADE) such as arginase, arginine decarboxylase (ADC), and arginine deiminase (ADI) could be effective in cancer therapy. The Arg auxotrophic cancerous cells like hepatocellular carcinoma, human colon cancer, leukemia, and breast cancer cells are sensitive to ADE treatment due to low expression of crucial enzymes argininosuccinate synthetase (ASS), argininosuccinate lyase (ASL), and ornithine transcarbamylase (OCT). These therapeutic enzyme treatments induce cell death through inducing autophagy, apoptosis, generation of oxidative species, i.e., oxidative stress, and arresting the progression and expansion of cancerous cells at certain cell cycle checkpoints. The enzymes are undergoing clinical trials and could be successfully exploited as potential anticancer agents in the future.

Tailor-made shape memory stents for therapeutic enzymes: A novel approach to enhance enzyme performance

Herein, our suggestion is to immobilize enzymes in-situ on absorbable shape-memory stents instead of injecting therapeutic enzymes into the blood. Chitosan (CHI)-based stents were tailored as novel support and the enzyme-immobilizing ability was elucidated using L-asparaginase (L-ASNase). For developing shape-memory stents, CHI-glycerol (GLY) solution was prepared and further blended with different ratios of polyethylene glycol (PEG), and polyvinyl alcohol (PVA). Afterward, the blends were modified by ionic crosslinking with sodium tripolyphosphate to obtain a shape-memory character. L-ASNase was included in the blends by using in-situ method before ionic crosslinking. The prepared stents, with or without L-ASNase, were comprehensively characterized by using several techniques. Collectively, immobilized L-ASNase exhibited much better performance in immobilization parameters than free one, thanks to its improved stability and reusability. For instance, CHI/GLY/PEG-3@L-ASNase retained about 70% of the initial activity after storage at 30 °C for 2 weeks, whereas the free form lost half of its initial activity. Besides, it retained 73.4% residual activity after 15 consecutive cycles. Most importantly, stent formulations exhibited ~60% activity in the bioreactor system after 4 weeks of incubation. Given the above results, shape-memory stents can be a promising candidate as a new platform for immobilization, especially in the blood circulation system.

Nanofibrous Formulation of Cyclodextrin Stabilized Lipases for Efficient Pancreatin Replacement Therapies

Enzyme replacement therapies (ERT) have been of great help over the past 30 years in the treatment of various lysosomal storage disorders, including chronic pancreatitis and its common complication, exocrine pancreatic insufficiency. Research shows that difficulties in designing such drugs can be overcome by using appropriate additives and various enzyme immobilization techniques. Cyclodextrins (CDs) can be considered as a promising additive for enzyme replacement therapies, as they are known to enhance the activity of enzymes in a complex process due to their specific binding. In this study, we investigated the formulation of lipases (from Aspergillus oryzae and Burkholderia cepacia) paired with different cyclodextrins in poly(vinyl alcohol) (PVA) nanofibers by electrospinning technique. We examined the effect of the presence of cyclodextrins and nanoformulation on the lipase activity. The rheological and morphological characterizations of precursors and nanofibers were also performed using a viscometer as well as electron and Raman microscope. We found that by selecting the appropriate CD:lipase ratio, the activity of the investigated enzyme could be multiplied, and cyclodextrins can support the homogeneous dispersion of lipases inside the solid formula. In addition, the entrapment of lipases in PVA nanofibers led to a significant increase in activity compared to the preformulated precursor. In this way, the nanofibrous formulation of lipases combining CDs as additives can provide an efficient and sustainable possibility for designing novel solid medicines in ERT.

Recent advances in user-friendly computational tools to engineer protein function

Progress in technology and algorithms throughout the past decade has transformed the field of protein design and engineering. Computational approaches have become well-engrained in the processes of tailoring proteins for various biotechnological applications. Many tools and methods are developed and upgraded each year to satisfy the increasing demands and challenges of protein engineering. To help protein engineers and bioinformaticians navigate this emerging wave of dedicated software, we have critically evaluated recent additions to the toolbox regarding their application for semi-rational and rational protein engineering. These newly developed tools identify and prioritize hotspots and analyze the effects of mutations for a variety of properties, comprising ligand binding, protein-protein and protein-nucleic acid interactions, and electrostatic potential. We also discuss notable progress to target elusive protein dynamics and associated properties like ligand-transport processes and allosteric communication. Finally, we discuss several challenges these tools face and provide our perspectives on the further development of readily applicable methods to guide protein engineering efforts.

Production of Cross-Linked Lipase Crystals at a Preparative Scale

The autoimmobilization of enzymes via cross-linked enzyme crystals (CLECs) has regained interest in recent years, boosted by the extensive knowledge gained in protein crystallization, the decrease of cost and laboriousness of the process, and the development of potential applications. In this work, we present the crystallization and preparative-scale production of reinforced cross-linked lipase crystals (RCLLCs) using a commercial detergent additive as a raw material. Bulk crystallization was carried out in 500 mL of agarose media using the batch technique. Agarose facilitates the homogeneous production of crystals, their cross-linking treatment, and their extraction. RCLLCs were active in an aqueous solution and in hexane, as shown by the hydrolysis of p-nitrophenol butyrate and α-methylbenzyl acetate, respectively. RCLLCs presented both high thermal and robust operational stability, allowing the preparation of a packed-bed chromatographic column to work in a continuous flow. Finally, we determined the three-dimensional (3D) models of this commercial lipase crystallized with and without phosphate at 2.0 and 1.7 Å resolutions, respectively.

Construction of Enzyme Nanoreactors to Enable Tumor Microenvironment Modulation and Enhanced Cancer Treatment

Enzymes play pivotal roles in regulating and maintaining the normal functions of all living systems, and some of them are extensively employed for diagnosis and treatment of diverse diseases. More recently, several kinds of enzymes with unique catalytic activities have been found to be promising options to directly suppress tumor growth and/or augment the therapeutic efficacy of other treatments by modulating the hostile tumor microenvironment (TME), which is reported to negatively impair the therapeutic efficacy of different cancer treatments. In this review, first a summary is presented on the chemical approaches utilized for the construction of distinct enzyme nanoreactors with well-retained catalytic performance and reduced immunogenicity. Then, the utilization of such enzyme nanoreactors in attenuating tumor hypoxia, modulating extracellular matrix, and amplifying tumor oxidative stress is discussed in depth. Afterward, some perspectives are presented on the future development of such enzyme nanoreactors in TME modulation and enhanced cancer treatment.

Catalase-Loaded Silica Nanoparticles Formulated via Direct Surface Modification as Potential Oxygen Generators for Hypoxia Relief

Enzymes are biological catalysts that have many potential industrial and biomedical applications. However, the widespread use of enzymes in the industry has been limited by their instability and poor recovery. In biomedical applications, systemic administration of enzymes has faced two main challenges: limited bioactivity mostly due to rapid degradation by proteases and immunogenic activity, since most enzymes are from nonhuman sources. Herein, we propose a robust enzyme-encapsulation strategy to mitigate these limitations. Catalase (CAT) was encapsulated in nanoporous silica nanoparticles (CAT-SiNPs) by first chemically modifying the enzyme surface with a silica precursor, followed by silica growth and finally poly(ethylene glycol) (PEG) conjugation. The formulation was carried out in mild aqueous conditions and yielded nanoparticles (NPs) with a mean diameter of 230 ± 10 nm and a concentration of 1.3 ± 0.8 × 10¹² NPs/mL. CAT-SiNPs demonstrated high enzyme activity, optimal protection from proteolysis by proteinase K and trypsin, and excellent stability over time. In addition, a new electrochemical assay was developed to measure CAT activity in a rapid, simple, and accurate manner without interference from chromophore usually present in biological samples. Concentrations of 2.5 × 10¹⁰ to 80 × 10¹⁰ CAT-SiNPs/mL not only proved to be nontoxic in cell cultures using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay but also conferred cell protection when cells were exposed to 1 mM hydrogen peroxide (H₂O₂). Finally, the ability of CAT-SiNPs to release oxygen (O₂) when exposed to H₂O₂ was demonstrated in vivo using a rat model. Following the direct injection of CAT-SiNPs in the left kidney, partial pressure of oxygen (pO₂) increased by more than 30 mmHg compared to the contralateral control kidney during the systemic infusion of safe levels of H₂O₂. This pilot study highlights the potential of CAT-SiNPs to generate O₂ to relieve hypoxia in tissues and potentially sensitize tumors against radiation therapy.

Enzyme/Nanocopper Hybrid Nanozymes: Modulating Enzyme-like Activity by the Protein Structure for Biosensing and Tumor Catalytic Therapy

Artificial enzymes with modulated enzyme-mimicking activities of natural systems represent a challenge in catalytic applications. Here, we show the creation of artificial Cu metalloenzymes based on the generation of Cu nanoparticles in an enzyme matrix. Different enzymes were used, and the structural differences between the enzymes especially influenced the controlled the size of the nanoparticles and the environment that surrounds them. Herein, we demonstrated that the oxidase-like catalytic activity of these copper nanozymes was rationally modulated by enzyme used as a scaffold, with a special role in the nanoparticle size and their environment. In this sense, these nanocopper hybrids have confirmed the ability to mimic a unique enzymatic activity completely different from the natural activity of the enzyme used as a scaffold, such as tyrosinase-like activity or as Fenton catalyst, which has extremely higher stability than natural mushroom tyrosinase. More interestingly, the oxidoreductase-like activity of nanocopper hybrids was cooperatively modulated with the synergistic effect between the enzyme and the nanoparticles improving the catalase activity (no peroxidase activity). Additionally, a novel dual (metallic and enzymatic activity) of the nanozyme made the highly improved catechol-like activity interesting for the design of 3,4-dihydroxy-l-phenylalanine (l-DOPA) biosensor for detection of tyrosinase. These hybrids also showed cytotoxic activity against different tumor cells, interesting in biocatalytic tumor therapy.

Rational Design and Construction of Active-Site Labeled Enzymes

With a growing amount of structural information of proteins, deciphering the linkage between the structure and function of these proteins is the next important task in structural genomics. To characterize the function of an enzyme at molecular level, placing a reporter on the active site of an enzyme can be a strategy to examine the dynamics of the interaction between enzyme and its substrate/inhibitor. In this chapter, we describe an approach of active-site labeling of enzyme for this purpose. Provided with the fabrication of a fluorescein-labeled AmpC β-lactamase as an example, we herein depict the methodology of a structure-based selection of the location in an enzyme's active site for bioconjugation and the preparation of the active-site labeled enzyme.