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Enzymatic Reaction Kinetics and Immobilization of Enzymes
Published in Debabrata Das, Soumya Pandit, Industrial Biotechnology, 2021
Enzymes are considered to be biocatalysts which are very specific with respect to the substrate. Enzymes are mostly proteins with active sites. The kinetics of the enzymatic reaction play an important role in biochemical processes. Most of the biochemical reactions are reversible in nature. The values of the kinetic constants are useful for designing the biochemical reactor. A major drawback of the enzymatic reaction process is the removal of enzymes after the completion of the process for the purification of the product. Enzymes are very costly. Therefore, it is necessary to find suitable devices such as immobilized enzymes in order to reuse the enzyme again. Immobilized enzymes are largely used in industry for the production of useful products, for analytical purposes and for medicinal uses. A major bottleneck of immobilized enzymatic reactions is the diffusion problem. This problem must be overcome for the maximization of product formation.
Immobilization of Biomolecules
Published in Anil Kumar Anal, Bionanotechnology, 2018
Different types of biomolecules are immobilized for different intended functions and applications. Immobilization of enzyme is widely practiced in biotechnological processes for cost reduction and efficient utilization of the enzymes. Immobilized enzymes refer to the physical confinement of enzymes in a certain defined space in such a way that the catalytic activities of enzymes are retained and facilitate repeated and continuous use (Tosa et al. 1966). Immobilized enzyme systems are used for production of regioselective and enantioselective compounds for biomedical applications (Lee et al. 2009a). Immobilized lipases are used for biosynthesis of polyesters (Idris and Bukhari 2011), and silica nanoparticles with immobilized laccase (oxidase enzyme) are used in wastewater treatment (Zimmermann et al. 2011). Other applications of immobilized enzyme include biorecognition element in biosensors, for instance, glucose oxidase (GO) immobilized on electrospun polyvinyl alcohol (PVA) and surface-modified carbon nanotubes used in glucose biosensors (Wen et al. 2011), enzyme horseradish peroxidase (HRP) immobilized on γ-aluminum trioxide nanoparticles/chitosan film-modified electrode used in hydrogen peroxide biosensors (Liu et al. 2011), and soluble plant invertase enzyme immobilized on composite of agarose-guar gum biopolymer matrix utilized in phenol biosensors (Bagal and Karve 2006).
Biological Strategies in Nanobiocatalyst Assembly
Published in Grunwald Peter, Biocatalysis and Nanotechnology, 2017
Ian Dominic F. Tabañag, Shen-Long Tsai
The utilization of enzymes on an industrial scale requires their reusability for a very long time since most chemical processes catalyzed by enzymes require its continuous use for both technical and economic reasons (Katchalski-Katzir, 1993; Bickerstaff Jr, 1997). To address the concerns on the enzyme instability characteristics and reusability, it has been found out that enzyme immobilization provides one of the best solutions to overcome these problems. The term “immobilized enzymes” refers to the “enzymes physically confined or localized in a certain defined region of space with retention of their catalytic abilities, and which can be used repeatedly and continuously” (Katchalski-Katzir, 1993). Furthermore, enzyme immobilization has been used to increase the overall activity and stability by maintaining a proper orientation of the enzyme molecules towards incoming substrates, and it may also function as an additional protection of the enzyme structure against inhibiting molecules and denaturation. The introduction of immobilization techniques has greatly improved the technical performance and economy of industrial processes (Bornscheuer and Buchholz, 2005).
Preparation of carrierized cellulase Cellulase@MIL-88B(Fe) and its enzymatic properties
Published in Green Chemistry Letters and Reviews, 2022
Erhong Zhang, Meng Wang, Xiaoliang Pan, Xinfeng Wang, Wenju Zhang
One of the most important goals of immobilized enzymes is their reusability in industrial applications. In this paper, Cellulase@MIL-88B(Fe) was used to hydrolyze CMC 10 times continuously under the same conditions to assess its reusability. Figure 6 shows the changes of residual activity of Cellulase@MIL-88B(Fe) after 10 uses. As can be seen from the figure, the Cellulase@MIL-88B(Fe) residual activity gradually decreased with the increase in the number of cycles. After 5 and 10 consecutive applications, Cellulase@MIL-88B(Fe) retained high residual activity at 90.10% and 78.37% of the initial activity, respectively. This indicates that Cellulase@MIL-88B(Fe) exhibits good operational stability, which is mainly due to the fact that cellulase is covalently immobilized on MIL-88B(Fe), so that the conformation of the enzyme molecule is restricted and not easily affected by external environmental factors. The reason for the substantial decrease in residual activity of Cellulase@MIL-88B(Fe) after eight repeated uses could be the denaturation of the cellulase molecule and degradation of the active site due to multiple repeated uses as well as the detachment of the enzyme from the carrier. Sillu et al.reported that cellulase immobilized on magnetic nanotubes retained 68.2% of its initial activity after seven uses (22). Li et al. demonstrated that immobilization of cellulase with carbon nanotubes and sodium alginate retained about 70% of the activity after the 7th application (17).
Remediation and improvement of 2,4-dichlorophenol contaminated soil by biochar-immobilized laccase
Published in Environmental Technology, 2021
Zhaobo Wang, Dajun Ren, Yusheng Zhao, Chaofan Huang, Shuqin Zhang, Xiaoqin Zhang, Chen Kang, Zhiqun Deng, Huiwen Guo
Since the 1960s, the immobilization technology has become an effective means to improve the stability of enzymes [17]. The immobilized enzyme not only inherits the highly efficient catalytic reaction characteristics of the free enzyme, but also has the advantages of improved stability, continuous and controllable reaction process, and reusability in most cases. Bayramglu, Park, and Yang et al. used magnetic chitosan, multi-walled carbon nanotubes and magnetic tubular mesoporous silica as carrier materials to immobilize laccase. The results showed that the stability and catalytic performance of laccase are improved by immobilization [18–20]. In addition, some studies have reported that laccase can be immobilized on polymer material [21], nanomaterial [22], and magnetic particle [23] to improve the stability [24,25].