Lipase immobilization into porous chitoxan beads: activities in aqueous and organic media and lipase localization

Amphiphilic Nanointerface: Inducing the Interfacial Activation for Lipase

Graphene-based materials are widely used in the field of immobilized enzymes due to their easily tunable interfacial properties. We designed amphiphilic nanobiological interfaces between graphene oxide (GO) and lipase TL (Thermomyces lanuginosus) with tunable reduction degrees through molecular dynamics simulations and a facile chemical modulation, thus revealing the optimal interface for the interfacial activation of lipase TL and addressing the weakness of lipase TL, which exhibits weak catalytic activity due to an inconspicuous active site lid. It was demonstrated that the reduced graphene oxide (rGO) after 4 h of ascorbic acid reduction could boost the relative enzyme activity of lipase TL to reach 208%, which was 48% higher than the pristine GO and 120% higher than the rGO after 48 h of reduction. Moreover, TL-GO-4 h's tolerance against heat, organic solvent, and long-term storage environment was higher than that of free TL. The drawbacks of strong hydrophobic nanomaterials on lipase production were explored in depth with the help of molecular dynamics simulations, which explained the mechanism of enzyme activity enhancement. We demonstrated that nanomaterials with certain hydrophilicity could facilitate the lipase to undergo interfacial activation and improve its stability and protein loading rate, displaying the potential of the extensive application.

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.

Magnetic nanoparticles: a versatile carrier for enzymes in bio-processing sectors

Many industrial processes experience the advantages of enzymes which evolved the demand for enzymatic technologies. The enzyme immobilisation technology using different carriers has trustworthy applications in industrial biotechnology as these techniques encompass varied advantages such as enhanced stability, activity along with reusability. Immobilisation onto nanomaterial is highly favourable as it includes almost all aspects of science. Among the various techniques of immobilisation, the uses of nanoparticles are remarkably well perceived as these possess high-specific surface area leading to high enzyme loadings. The magnetic nanoparticles (MNPs) are burgeoning in the field of immobilisation as it possess some of the unique properties such as high surface area to volume ratio, uniform particle size, biocompatibility and particularly the recovery of enzymes with the application of an external magnetic field. Immobilisation of industrially important enzymes onto nanoparticles offers overall combined benefits. In this review, the authors here focus on the current scenario in synthesis and functionalisation of MNPs which makes it more compatible for the enzyme immobilisation and its application in the biotechnological industries.

Immobilization of Enzymes into a Polyionic Hydrogel: ChitoXan

Three enzymes were immobilized onto polyionic hydrogel, ChitoXan, obtained by complexation between chitosan and xanthan. The biocatalysts used were two proteases (protease type XIX from Fungal d’Aspergillus sojae and the trypsin type II.S from Porcine Pancreas) and a lipase (lipase Type VII from Candida rugosa). The immobilization efficiencies and the relative activities were investigated for these enzymes. The immobilization efficiencies changed with each enzyme and varied between 53 and 80%. Good relative activities were found for the lipase Type VII from Candida rugosa and the protease type XIX from Fungal d’Aspergillus sojae. For the latter, the influence of several factors were studied: molarity of the storage buffer, storage temperature and time of hydrogel, and the enzyme concentration. For the immobilized lipase, hydrolysis of olive oil in aqueous and organic media has been compared. This study confirmed that the lipase modified the external and internal structure of the hydrogel from fibrillar to the formation of globular structures in the presence of lipases.

Controlled release of lipase from Candida rugosa loaded into hydrogels of N-isopropylacrylamide and itaconic acid

The series of poly(N-isopropylacrylamide-co-itaconic acid) hydrogels, with lipase from Candida rugosa as a model protein, were synthesized by free radical copolymerization. The composition of hydrogels was varied by monomers ratio, crosslinking agent concentration and amounts of lipase, which was loaded by in situ polymerization. All samples were characterized regarding morphology. The investigation of hydrogel swelling properties revealed their pH and temperature sensitive character. Protein loading efficiency, release profiles and the specific activity yield of the released lipase were also investigated as a function of hydrogel composition, protein content and pH, at the physiological temperature of 37 °C. Copolymers of N-isopropylacrylamide and itaconic acid presented high lipase loading efficiency. Another very important feature of these copolymers was that the protein release kinetic strongly depended on the pH value of the medium. The diffusion exponents values around 1 denoted that these hydrogel compositions could be adjusted to follow near zero-order kinetics. Namely, hydrogel formulations released low amounts of lipase at pH 2.20, but much higher released protein quantities were observed at pH 6.80 enabling these copolymers to be attractive candidates as site specific protein oral drug delivery systems.

Noncovalent immobilization of Pectinesterase (Prunus armeniaca L.) onto bentonite

In this work, pectinesterase isolated from Malatya apricot was immobilized onto acid-treated bentonite surface by simple adsorption at pH 9.0. The properties of free and immobilized enzyme were defined. The effect of various factors such as pH, temperature, heat, and storage stability on immobilized enzyme were investigated. Optimum pH and temperature were determined to be 9.0 and 50 degrees C, respectively. Kinetic parameters of the immobilized enzyme (Km and Vmax values) were also determined as 0.51 mM of the Km and 14.6 micromol min(-1) mg(-1) of the Vmax. No drastic change was observed in the Km value after immobilization. The Vmax value of immobilized enzyme was 8.4-fold bigger than those of free enzyme. Thermal and storage stability experiments were carried out. The patterns of heat stability indicated that the immobilization process tends to stabilize the enzyme. The properties of the immobilized enzyme were compared to those of the free enzyme.

Physical immobilization of Rhizopus oryzae lipase onto cellulose substrate: activity and stability studies

Rhizopus oryzae lipase (ROL) was immobilized by adsorption onto oxidized cellulose fibers and regenerated films. The maximum adsorption level increases with the raise in the amount of carboxylic groups on cellulose surface confirming that adsorption is being governed mainly by electrostatic interaction between the enzyme and the substrate. This hypothesis was further confirmed by zeta-potential measurements showing a decrease in the zeta-potential of the fibers after enzyme adsorption. XPS analysis showed an intensification of the N 1s peak attesting the presence of the enzyme on the surface. The effect of temperature, pH and solvent polarity on the immobilized enzyme activity and stability was investigated. The catalytic esterification of oleic acid with n-butanol has been carried on using hexane as an organic solvent. A high conversion yield was obtained (about 80%) at 37 degrees C with a molar ratio of oleic acid to butanol 1:1 and 150IU immobilized lipase. The adsorption achieved two successive cycles with the same efficiency, and started to lose its activity during the third cycle.

Catalytic activity of lipase immobilized onto ultrathin films of cellulose esters

Ultrathin (approximately 2.0 nm) films of cellulose acetate (CA), cellulose acetate propionate (CAP), and cellulose acetate butyrate (CAB) supported on Si wafers have been prepared by adsorption and characterized by means of ellipsometry, atomic force microscopy (AFM), and contact angle measurements. CA, CAP, and CAB ultrathin films were characterized in air just after their formation and after annealing under reduced pressure at temperature higher than the corresponding melt temperature. Upon annealing, CA, CAP, and CAB ultrathin films became smoother and more hydrophobic, evidencing molecular reorientation at the solid-air interface. CA, CAP, and CAB films were used as supports for the immobilization of lipase. The adsorption of lipase onto annealed films was more pronounced than that onto untreated films, showing the strong affinity of lipase for the more hydrophobic substrates. Enzymatic activity was evaluated by a standard procedure, namely, (spectrophotometric) measurement of p-nitrophenol, the product formed from the hydrolysis of p-nitrophenyl dodecanoate (p-NPD). Lipase immobilized onto hydrophobic films exhibited higher activity than that of free lipase and could be recycled three times while retaining relatively high activity (loss of ca. 30% of original enzymatic activity). The effect of storing time on the activity of immobilized lipase was studied. Compared with free lipase, that immobilized onto more hydrophobic films retained 70% activity after 1 month. More importantly, the latter level of activity is similar to that of free lipase. However, lipase immobilized onto more hydrophilic films retained 50% and 30% activity after 20 and 30 days, respectively. These results are explained in terms of surface wettability and the contribution of the interactions between the polar residues of lipase and the glucopyranosyl moieties of cellulose ester to maintain the natural conformation of immobilized enzyme.

Lipase immobilized by different techniques on various support materials applied in oil hydrolysis

Batch hydrolysis of olive oil was performed by Candida rugosa lipase immobilized on Amberlite IRC-50 and Al2O3. These two supports were selected out of 16 carriers: inorganic materials (sand, silica gel, infusorial earth Al2O3), inorganic salts (CaCO3, CaSO4), ion-exchange resins (Amberlite IRC-50 and IR-4B, Dowex 2X8), a natural resin (colophony), a natural biopolymer (sodium alginate), synthetic polymers (polypropylene, polyethylene) and zeolites. Lipase immobilization was carried out by simple adsorption adsorption followed by cross-linking, adsorption on ion-exchange resins combined adsorption and precipitation, pure precipitation and gel entrapment. The suitability of the supports and techniques for the immobilization of lipase was evaluated by estimating the enzyme activity, protein loading immobilization efficiency and reusability of the immobilizates. Most of the immobilizates exhibited either a low enzyme activity or difficulties during the hydrolytic reaction. Only those prepared by ionic adsorption on Amberlite IRC-50 and by combined adsorption and precipitation on Al2O33 showed better activity, 2000 and 430 U/g support, respectively, and demonstrated satisfactory behavior when used repeatedly. The hydrolysis was studied as a function of several parameters: surfactant concentration, enzyme concentration, pH and temperature. The immobilized preparation with Amberlite IRC-50 was stable and active in the whole range of pH (4 to 9) and temperature (20 to 50 ?C), demonstrating a 99%degree of hydrolysis. In repeated usage, it was stable and active having a half-life of 16 batches which corresponds to an operation time of 384 h. Its storage stability was remarkable too, since after 9 months it had lost only 25 % of the initial activity. The immobilizate with Al2O3 was less stable and less active. At optimal environmental conditions, the degree of hydrolysis did not exceed 79 %. In repeated usage, after the fourth batch, the degree of hydrolysis was reduced to 53.5 %.