Stability of immobilized porcine pancreas lipase on mesoporous chitosan beads: A comparative study

Chitosan as a Promising Support of a CDH Activity Preservation System for Biomedical and Industrial Applications

Cellobiose dehydrogenase (CDH) is an extracellular hemoflavoprotein catalyzing the oxidation reaction of β-1,4-glycosidic-bonded sugars (lactose or cellobiose), which results in the formation of aldobionic acids and hydrogen peroxide as a byproduct. The biotechnological application of CDH requires the immobilization of the enzyme on a suitable support. As a carrier of natural origin used for CDH immobilization, chitosan seems to increase the catalytic potential of the enzyme, especially for applications as packaging in the food industry and as a dressing material in medical applications. The present study aimed to immobilize the enzyme on chitosan beads and determine the physicochemical and biological properties of immobilized CDHs obtained from different fungal sources. The chitosan beads with immobilized CDHs were characterized in terms of their FTIR spectra or SEM microstructure. The most effective method of immobilization in the proposed modification was the covalent bonding of enzyme molecules using glutaraldehyde, resulting in efficiencies ranging from 28 to 99%. Very promising results, compared to free CDH, were obtained in the case of antioxidant, antimicrobial, and cytotoxic properties. Summarizing the obtained data, chitosan seems to be a valuable material for the development of innovative and effective immobilization systems for biomedical applications or food packaging, preserving the unique properties of CDH.

Efficient screening of pancreatic lipase inhibitors from cod meat hydrolysate through ligand fishing strategy

Obesity has become an increasingly serious public health problem. Pancreatic lipase (PL) is identified as a ideal target for the prevention and treatment of obesity. Orlistat, the only approved PL inhibitor (PLI), is a powerful weight loss drug but has many side effects. Therefore, there is an urgent need to discover powerful PLIs with high safety. Protein hydrolysate has been demonstrated to be a treasure trove of PLIs, but recognizing responsible functional peptides from them is like looking for a needle in a haystack. In this work, we synthesized and optimized a PL ligand fishing model (PLLFM) using magnetic nanoparticles (MNPs), then PLLFM was used to quickly fish out potential PLIs from the Cod meat hydrolysate (CMH). Finally, two new PLIs, GSPPPSG and KLEGDLK were identified with IC₅₀ of 0.60 and 1.08 mg/mL, respectively. The Lineweaver-Burk diagram showed that GSPPPSG is a non-competitively dominant mixed-type PLI, whereas KLEGDLK is a competitive inhibitory-type PLI. Moreover, molecular docking suggested that both peptides can stably bind to the key amino acid residues of the PL active site, mainly through hydrogen bonding, hydrophobic, and electrostatic interactions. In general, we not only established a method to rapidly fish out potential PLIs from protein hydrolysate, but also provided safe and efficient lead compounds for the development of novel diet foods or drugs.

Chemical and physical Chitosan modification for designing enzymatic industrial biocatalysts: How to choose the best strategy?

Chitosan is one of the most abundant natural polymer worldwide, and due to its inherent characteristics, its use in industrial processes has been extensively explored. Because it is biodegradable, biocompatible, non-toxic, hydrophilic, cheap, and has good physical-chemical stability, it is seen as an excellent alternative for the replacement of synthetic materials in the search for more sustainable production methodologies. Thus being, a possible biotechnological application of Chitosan is as a direct support for enzyme immobilization. However, its applicability is quite specific, and to overcome this issue, alternative pretreatments are required, such as chemical and physical modifications to its structure, enabling its use in a wider array of applications. This review aims to present the topic in detail, by exploring and discussing methods of employment of Chitosan in enzymatic immobilization processes with various enzymes, presenting its advantages and disadvantages, as well as listing possible chemical modifications and combinations with other compounds for formulating an ideal support for this purpose. First, we will present Chitosan emphasizing its characteristics that allow its use as enzyme support. Furthermore, we will discuss possible physicochemical modifications that can be made to Chitosan, mentioning the improvements obtained in each process. These discussions will enable a comprehensive comparison between, and an informed choice of, the best technologies concerning enzyme immobilization and the application conditions of the biocatalyst.

Different strategies for the lipase immobilization on the chitosan based supports and their applications

Immobilized enzymes have received incredible interests in industry, pharmaceuticals, chemistry and biochemistry sectors due to their various advantages such as ease of separation, multiple reusability, non-toxicity, biocompatibility, high activity and resistant to environmental changes. This review in between various immobilized enzymes focuses on lipase as one of the most practical enzyme and chitosan as a preferred biosupport for lipase immobilization and provides a broad range of studies of recent decade. We highlight several aspects of lipase immobilization on the surface of chitosan support containing various types of lipase and immobilization techniques from physical adsorption to covalent bonding and cross-linking with their benefits and drawbacks. The recent advances and future perspectives that can improve the present problems with lipase and chitosan such as high-price of lipase and low mechanical resistance of chitosan are also discussed. According to the literature, optimization of immobilization methods, combination of these methods with other techniques, physical and chemical modifications of chitosan, co-immobilization and protein engineering can be useful as a solution to overcome the mentioned limitations.

Immobilization of α-amylase enzyme on a protein @metal-organic framework nanocomposite: A new strategy to develop the reusability and stability of the enzyme

Metal-organic structures (MOFs) have been designed for a wide range of applications due to their high porosity, large surface area, and flexibility. For the first time in this work, the successful immobilization of α-amylase is confirmed by the use of ZIF-8 as easy and good support. The morphology, functional groups, and chemical composition of the support and immobilized α-amylase were tested using different methods such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and thermal gravimetric analysis (TGA). The enzymatic activities of the immobilized olibanum-bovine serum albumin@zeolitic imidazolate frameworks nanocomposite (OLB/BSA@ZIF-8)-α-amylase were compared with the free one. The pH and thermal stability of the OLB/BSA@ZIF-8-α-amylase were significantly enhanced compared to the free enzyme. The OLB/BSA@ZIF-8-α-amylase displayed excellent long-term storage stability, which could protect more than 90% of the initial activity for 8 weeks. Besides, the OLB/BSA@ZIF-8-α-amylase had high reusability, which showed a high degree of activity (more than 81%) after 20 cycles. This is the first study that uses OLB/BSA@ZIF-8 nanocomposite as immobilizing support for the immobilization of α-amylase. Improved catalytic efficiency (V_max/K_m) values, reusability, and storage stability of immobilized α-amylase can make it suitable in industrial and biotechnological applications.

Biodegradation of bisphenol A by the immobilized laccase on some synthesized and modified forms of zeolite Y

Bisphenol A (BPA) is an environmental pollutant with adverse effects on different ecosystems. In this study, immobilized laccase enzymes onto inorganic supports were used to remove BPA. Laccase was successfully immobilized on sodium zeolite Y (NaY) and its modified desilicated (DSY) and dealuminated (DAY) forms. NaY-based supports were instrumentally characterized. The immobilized laccase on NaY (laccase@NaY), desilicated (laccase@DSY), and dealuminated (laccase@DAY) forms showed significant improvement on immobilization yield (IY%) and efficiency (IE%). Laccase@DSY and laccase@NaY showed IY% = 73.18 ± 3.33 % and 46.23 ± 1.81 % and IE% = 94.50 ± 1.86 %, and 74.39 ± 1.41 %, respectively, whereas IY% and IE% for laccase@DAY were achieved as 81.12 ± 1.32 % and 98.56 ± 2.93 %, respectively. The supports also increased the enzyme characteristics such as pH-temperature range, catalytic stability, and reusability. K_m values were 0.73 ± 0.05, 0.26 ± 0.09, 0.31 ± 0.5, and 1.01 ± 0.03 mM for laccase@NaY, laccase@DAY, laccase@DSY, and the free enzyme, respectively. The enzyme demonstrated higher biodegradation ability of bisphenol A upon immobilization on the supports compared to that of the soluble enzyme. A bio-removal yield of 86.7 % was obtained considering three parameters including amount of laccase@DAY (8 U mg^-1), concentration of BPA (0.5 mM), and treatment time (1 h) based on response surface methodology (RSM). Biodegradation metabolites (49 ± 5.8 %) and unconverted BPA (14 ± 5.2 %) were analyzed by gas chromatography-mass spectrometry.

Biochemical aspects of lipase immobilization at polysaccharides for biotechnology

The design of immobilized enzyme preparations is an important and relevant area of modern sciences and technologies. Immobilization of enzymes from animal sources (component I) on natural carriers (component II) increases the system stability by protecting the active site of the enzyme from deactivation; facilitates the separation and accelerates the recovery of the enzyme. This makes reuse possible and provides a significant reduction in operating costs. Hydrolytic enzymes (such as lipases) and polysaccharides (such as chitosan) are the most promising of such pairs of components. The main attention here is devoted to the discussion on lipase immobilization on polysaccharide (mainly - chitin and chitosan). Based on the analysis of the available literature, the most adequate method is the immobilization of lipase from porcine pancreas (LPP) on polysaccharide particles (such as chitin or chitosan) pre-treated with ultrasound (to increase the particle surface area) and glutaraldehyde (for particle activation) that shows reasonably high LPP activity and stability. In order to increase further the activity of the lipase, some authors proposed to incorporate a spacer in the form of 1,3-diaminopropane (or 1,3-diaminobutane) prior to activation of the surface of the chitosan particles. In particular cases, the use of chitin (instead of chitosan) may be an alternative solution for biotechnological applications. Recently the idea of constructing "supramolecular enzyme systems" realized in the so-called "coimmobilized multienzymatic systems" strategy. The most fascinating example is the combined assay of a mixture of native LPP, glycerol kinase (from Cellulomonas) and glycerol-3-phosphate oxidase (from Aerococcus viridans) linked by glutaraldehyde to chitosan (as shell for inorganic nanoparticle core). This material was placed on a Pt-electrode as biosensor and was successfully applied for amperometric determination of the triglyceride level in the serum of healthy and diseased person. Thus, the whole innovative research-production sequence is described by Aggarwal V. and Pundir C.S.: from simple components to advanced material and further biomedical application. Thus, the following approach of lipase immobilization appears the most promising for future applications: a few types of lipases or the combination of LPP with some other enzymes immobilized simultaneously on multifunctional carriers (as nanohybrids of inorganic core and polysaccharide shell).

Synthesis and properties of porous CLEAs lipase by the calcium carbonate template method and its application in biodiesel production

In this work, porous cross-linked enzyme aggregates (p-CLEAs) were synthesized by the in situ co-precipitation method using CaCO₃ microparticles as templates. The preparation procedure involved the immobilization of crude lipase as CLEAs via precipitation with ammonium sulfate and entrapping these lipase molecules into the CaCO₃ templates, followed by DTT (dithiothreitol)-induced assembly of lipase molecules to form lipase microparticles (lipase molecules were assembled into microparticles internally using disulfide bonds within the lipase molecules as the molecular linkers and stimulated by dithiothreitol); finally, the removal of CaCO₃ templates was performed by EDTA to form pores in CLEAs. The scanning electron microscopy analysis of p-CLEAs showed a porous structure. p-CLEAs showed obvious improvement in thermal stability (after incubation at 65 °C, p-CLEAs lipase retained 86% relative activity, while free lipase retained only 33.67%) and pH stability (p-CLEAs relative activity was over 90% while for free lipase, the relative activity ranged from 72% to 89% from pH 6 to 9) than free lipase and could hold relatively high activity retention without activity loss at 4 °C for more than six months. The application of p-CLEAs in producing biodiesel showed a higher degree of conversion. The conversion of fatty acid methyl ester (FAME) was 89.7%; this value was higher by approximately 7.4% compared to that of the conventional CLEAs under the optimized conditions of a methanol–oil molar ratio of 6 : 1, with a p-CLEAs lipase dose of 20% and water content of 3% at 45 °C for 24 h. The FAME conversion remained greater than 70% even after reusing the p-CLEAs lipase for 8 reactions. The results demonstrated that the p-CLEAs lipase is suitable for applications in the preparation of biodiesel.

Porous cross-linked enzyme aggregates (p-CLEAs) were synthesized. This p-CLEAs presented a complete structure with abundant channels, large specific surface and more efficient catalytic effect compared with conventional CLEAs.

Bamboo (Phyllostachys pubescens) as a Natural Support for Neutral Protease Immobilization

Lignin polymers in bamboo (Phyllostachys pubescens) were decomposed into polyphenols at high temperatures and oxidized for the introduction of quinone groups from peroxidase extracted from bamboo shoots and catalysis of UV. According to the results of FT-IR spectra analysis, neutral proteases (NPs) can be immobilized on the oxidized lignin by covalent bonding formed by amine group and quinone group. The optimum condition for the immobilization of NPs on the bamboo bar was obtained at pH 7.0, 40 °C, and duration of 4 h; the amount of immobilized enzyme was up to 5 mg g^-1 bamboo bar. The optimal pH for both free NP (FNP) and INP was approximately 7.0, and the maximum activity of INP was determined at 60 °C, whereas FNP presented maximum activity at 50 °C. The K_m values of INP and FNP were determined as 0.773 and 0.843 mg ml^-1, respectively; INP showed a lower K_m value and V_max, than FNP, which demonstrated that INP presented higher affinity to substrate. Compared to FNP, INP showed broader thermal and storage stability under the same trial condition. With respect to cost, INP presented considerable recycling efficiency for up to six consecutive cycles.

Enhanced catalytic stability of lipase immobilized on oxidized and disulfide-rich eggshell membrane for esters hydrolysis and transesterification

Eggshell membrane (ESM) is an industrial waste that is available in abundance from food industry. Present study investigated the physicochemical properties of oxidized ESM and compared the efficiency of ESM and oxidized ESM as carrier for Burkholderia cepacia lipase (BCL) used in esters hydrolysis and transesterification. Following oxidation treatment, FTIR analysis and Ellman's assay showed amino acid cysteine in ESM was oxidized to form disulfide bond-containing cystine. In addition, AFM analysis showed ESM which exhibited a highly porous filamentous structure appeared to be coalesce following oxidation treatment. Oxidized ESM also showed reduced porosity (38.67%) in comparison to native ESM (51.65%). BCL were successfully immobilized on oxidized ESM through carrier activation method (enzyme loading of 5.01mg protein/g oxidized ESM). These immobilized lipase demonstrated significantly (P<0.05) enhanced catalytic stability with close to 100% of initial hydrolysis (12.03±0.29mmol/min/g) activity; and more than 85% of its initial transesterification (7.83±0.05) activity for at least 10 consecutive runs. Enhanced catalytic stability of BCL immobilized on oxidized ESM might be due to stabilization of the protein structure in oxidized ESM by disulfide bonds which helped formation of a stable bonding with BCL.