Engineered tyrosinases with broadened bio-catalysis scope: immobilization using nanocarriers and applications

A Bibliometric Analysis: Current Perspectives and Potential Trends of Enzyme Thermostability from 1991-2022

Thermostability is considered a crucial parameter to evaluate the viability of enzymes in industrial applications. Over the past 31 years, many studies have been reported on the thermostability of enzymes. However, there is no systematic bibliometric analysis of publications on the thermostability of enzymes. In this study, 16,035 publications related to the thermostability of enzymes were searched and collected, showing an increasing annual trend. China contributed the most publications, while the United States had the highest citation count. International Journal of Biological Macromolecules is the most productive journal in the research field. Moreover, Chinese acad sci and Khosro Khajeh are the most active institutions and prolific authors in the field, respectively. Analysis of references with the strongest citation bursts and keyword co-occurrences, magnetic nanoparticles, metal-organic frameworks, molecular dynamics, and rational design are current hot spots and significant future research directions. This study is the first comprehensive bibliometric analysis summarizing trends and developments in enzyme thermostability research. Our findings could provide scholars with an understanding of the fundamental knowledge framework of the field and identify recent potential hotspots and research trends that could facilitate the discovery of collaboration opportunities.

Use of tyrosinase-inorganic salt hybrid nanoflowers and tyrosinase-MOF hybrid composites for elimination of phenolic pollutants from industrial wastewaters

Removal of phenolic pollutants from industrial wastewaters is always an important practical problem. Use of enzymes for dephenolization provides a green solution. In this work, enzymatic methods were developed by employing mushroom tyrosinase immobilized as enzyme-Cu₃(PO₄)₂ hybrid nanoflowers and enzyme-metal organic framework (i.e., ZIF-8 and HKUST-1) hybrid composites, which were shown to be superior to processes mediated by tyrosinase immobilized on other supports in both dephenolization efficiency and reusability. Comparatively, tyrosinase@Cu₃(PO₄)₂ and tyrosinase@HKUST-1 were better than tyrosinase@ZIF-8 in both specific activity and dephenolization efficiency. Typical phenolic pollutants, including 3 monophenols (phenol, p-cresol, p-chlorophenol) and 3 bisphenols (BPA, BPB, BPF), can be completely eliminated within 0.5-4 h. The dephenolization order was discussed based on the enzyme's substrate specificity. The operability and reusability of these hybrid biocomposites were highly improved by entrapping into alginate gels or by incorporating with modified magnetic Fe₃O₄ nanoparticles. Particularly, the magnetic biocatalyst was prepared via a facile one-pot/one-step de novo synthetic strategy, optimized by using response surface methodology (RSM). The as-prepared magnetic tyrosinase@mHKUST-1 retained a high dephenolization efficiency of 81% after 10 cycles and was effective for continuous dephenolization for at least 24 h. These hybrid biocomposites were also successfully applied to treatment of real industrial wastewater from a coke plant.

Tyrosinase Immobilization Strategies for the Development of Electrochemical Biosensors-A Review

The development of enzyme biosensors has successfully overcome various challenges such as enzyme instability, loss of enzyme activity or long response time. In the electroanalytical field, tyrosinase is used to develop biosensors that exploit its ability to catalyze the oxidation of numerous types of phenolic compounds with antioxidant and neurotransmitter roles. This review critically examines the main tyrosinase immobilization techniques for the development of sensitive electrochemical biosensors. Immobilization strategies are mainly classified according to the degree of reversibility/irreversibility of enzyme binding to the support material. Each tyrosinase immobilization method has advantages and limitations, and its selection depends mainly on the type of support electrode, electrode-modifying nanomaterials, cross-linking agent or surfactants used. Tyrosinase immobilization by cross-linking is characterized by very frequent use with outstanding performance of the developed biosensors. Additionally, research in recent years has focused on new immobilization strategies involving cross-linking, such as cross-linked enzyme aggregates (CLEAs) and magnetic cross-linked enzyme aggregates (mCLEAs). Therefore, it can be considered that cross-linking immobilization is the most feasible and economical approach, also providing the possibility of selecting the reagents used and the order of the immobilization steps, which favor the enhancement of biosensor performance characteristics.

Tailoring Lignin-Based Spherical Particles as a Support for Lipase Immobilization

Lignin-based spherical particles have recently gained popularity due to their characteristic and the usage of biopolymeric material. In this study, lignin-based spherical particles were prepared using choline chloride at different pH values, ranging from 2 to 10. Their dispersive, microstructural, and physicochemical properties were studied by a variety of techniques, including scanning electron microscopy, Fourier transform infrared spectroscopy, and zeta potential analysis. The best results were obtained for the particles prepared at pH 5 and 7, which had a spherical shape without a tendency to form aggregates and agglomerates. The lignin-based spherical particles were used for the immobilization of lipase, a model enzyme capable of catalyzing a wide range of transformations. It was shown that the highest relative activity of immobilized lipase was obtained after 24 h of immobilization at 30 °C and pH 7, using 100 mg of the support. Moreover, the immobilized lipase exhibited enhanced stability under harsh process conditions, and demonstrated high reusability, up to 87% after 10 cycles, depending on the support used. In the future, the described approach to enzyme immobilization based on lignin spheres may play a significant role in the catalytic synthesis of organic and fine chemicals, with high utility value.

Expanding the bio-catalysis scope and applied perspectives of nanocarrier immobilized asparaginases

l-asparaginase is an essential enzyme in medicine and a well-known chemotherapeutic agent. This enzyme's importance is not limited to its use as an anti-cancer agent; it also has a wide variety of medicinal applications. Antimicrobial properties, prevention of infectious disorders, autoimmune diseases, and canine and feline cancer are among the applications. Apart from the healthcare industry, its importance has been identified in the food industry as a food manufacturing agent to lower acrylamide levels. When isolated from their natural habitats, they are especially susceptible to different denaturing conditions due to their protein composition. The use of an immobilization technique is one of the most common approaches suggested to address these limitations. Immobilization is a technique that involves fixing enzymes to or inside stable supports, resulting in a heterogeneous immobilized enzyme framework. Strong support structures usually stabilize the enzymes' configuration, and their functions are maintained as a result. In recent years, there has been a lot of curiosity and focus on the ability of immobilized enzymes. The nanomaterials with ideal properties can be used to immobilize enzymes to regulate key factors that determine the efficacy of bio-catalysis. With applications in biotechnology, immunosensing, biomedicine, and nanotechnology sectors have opened a realm of opportunities for enzyme immobilization.