Immobilization of Candida rugosa lipase and some properties of the immobilized enzyme

Immobilisation of Candida rugosa lipase on a highly hydrophobic support: A stable immobilised lipase suitable for non-aqueous synthesis

Lipase from Candida rugosa (CrL) was immobilised on highly hydrophobic, octadecyl methacrylate resin (Lifetech™ ECR8806M) via interfacial adsorption. The aim was to produce a stable biocatalyst suitable for use in a range of lipid-modifying reactions. Immobilisation was carried out in 10 mM phosphate buffer (pH 6.0) over 24 h at 21 °C. High protein binding of 58.7 ± 4.9 mg/g dry support accounted for ∼53 % of the applied protein. The activity recovery against tributyrin was 74.0 ± 1.1 %. The specific activity of immobilised CrL against tributyrin was considerably higher than that of Novozym® 435, at 1.79 ± 0.05 and 1.08 ± 0.04 U/mg bound protein, respectively. Incubation with high concentrations (10 % w/v) of both Triton X-100 and SDS resulted in only a small reduction in immobilised lipase activity. Solvent-free synthesis of glycerides by the FFA-saturated immobilised CrL was successful over 6 reaction cycles, with no apparent loss of activity.

Enzymatic esterification of oleic acid by Candida rugosa lipase immobilized onto biochar

The immobilization of Candida rugosa lipase (CRL) onto biochar was studied in a series of batch experiments. CRL sorption behavior was evaluated as a function of pH, enzyme concentration, temperature and ionic strength. As the immobilized lipase was used for the catalytic esterification of oleic acid, its resistance to solvents and thermal stability were evaluated. CRL adsorption increased by increasing temperature, and with higher pH, reaching a maximum at pH 7.0. Immobilization increased lipase stability at 40 °C by more than 80% when compared to the free enzyme. Moreover, immobilized CRL showed high stability in the presence of tert-butanol, which prevents premature deactivation of the enzyme caused by alcohols during the reaction. Immobilization of CRL increased the oleic acid conversion rate. Our results suggest that biochar is a highly promising material for the immobilization of CRL lipase for the catalytic production of esters.

Investigating Enzyme Activity of Immobilized Candida rugosa Lipase

Candida rugosa lipase is a food-grade enzyme that is extensively utilized in the dairy processing industry for milk fat hydrolysis. The enzyme is mainly employed to modify the fatty acid chain length that results in the enhancement of flavors. The hydrolytic activities of C. rugosa lipase (fungal source) in its free and immobilized forms were investigated at different pH and temperature settings. The main objective of this study was to understand how different support materials (Celite-545, Sephadex G-25, and chitosan) and immobilization techniques alter lipase activity and stability. Our results indicated that hydrolytic activity increased significantly with immobilization on Celite-545. In general, immobilization resulted in considerable improvements in the stability of the enzyme with variations in pH and temperature. Immobilization on Celite-545 led to the highest catalytic efficiency. Remarkable improvements in the recovery and reusability of the immobilized lipases were noted. Comparatively, the acetone immobilization procedure resulted in higher activities than alcohol immobilization. In conclusion, the activity of C. rugosa lipase was enhanced most significantly when immobilized on Celite-545 using acetone as an adsorption solvent.

Tailoring recombinant lipases: keeping the His-tag favors esterification reactions, removing it favors hydrolysis reactions

We determined the effect of the His-tag on the structure, activity, stability and immobilization of LipC12, a highly active lipase from a metagenomic library. We purified LipC12 with a N-terminal His-tag and then removed the tag using tobacco etch virus (TEV) protease. Circular dichroism analysis showed that the overall structure of LipC12 was largely unaffected by His-tag removal. The specific hydrolytic activities against natural and artificial substrates were significantly increased by the removal of the His-tag. On the other hand, His-tagged LipC12 was significantly more active and stable in the presence of polar organic solvents than untagged LipC12. The immobilization efficiency on Immobead 150 was 100% for both forms of LipC12 and protein desorption studies confirmed that the His-tag does not participate in the covalent binding of the enzyme. In the case of immobilized LipC12, the His-tag negatively influenced the hydrolytic activity, as it had for the free lipase, however, it positively influenced the esterification activity. These results raise the possibility of tailoring recombinant lipases for different applications, where the His-tag may be retained or removed, as appropriate for the desired activity.

Improving the thermostability and optimal temperature of a lipase from the hyperthermophilic archaeon Pyrococcus furiosus by covalent immobilization

A recombinant thermostable lipase (Pf2001Δ60) from the hyperthermophilic Archaeon Pyrococcus furiosus (PFUL) was immobilized by hydrophobic interaction on octyl-agarose (octyl PFUL) and by covalent bond on aldehyde activated-agarose in the presence of DTT at pH = 7.0 (one-point covalent attachment) (glyoxyl-DTT PFUL) and on glyoxyl-agarose at pH 10.2 (multipoint covalent attachment) (glyoxyl PFUL). The enzyme's properties, such as optimal temperature and pH, thermostability, and selectivity, were improved by covalent immobilization. The highest enzyme stability at 70°C for 48 h incubation was achieved for glyoxyl PFUL (around 82% of residual activity), whereas glyoxyl-DTT PFUL maintained around 69% activity, followed by octyl PFUL (27% remaining activity). Immobilization on glyoxyl-agarose improved the optimal temperature to 90°C, while the optimal temperature of octyl PFUL was 70°C. Also, very significant changes in activity with different substrates were found. In general, the covalent bond derivatives were more active than octyl PFUL. The E value also depended substantially on the derivative and the conditions used. It was observed that the reaction of glyoxyl-DTT PFUL using methyl mandelate as a substrate at pH 7 presented the best results for enantioselectivity (E = 22) and enantiomeric excess (ee (%) = 91).

Synthesis of phytosteryl ester containing pinolenic acid in a solvent-free system using immobilized Candida rugosa lipase

Phytosteryl ester synthesized with pinolenic acid (PLA) from pine nut oil is expected to have features of both phytosterol and PLA. In this study, lipase from Candida rugosa (CRL) was immobilized and then used to optimize conditions for synthesis of phytosteryl ester containing PLA. Lewatit VP OC 1600, a macroporous hydrophobic resin, was selected as the best carrier, and the optimum condition for the immobilization of CRL was established. With immobilized CRL prepared, synthesis of phytosteryl ester with fatty acid from pine nut oil was carried out. Parameters investigated were temperature, molar ratio (phytosterol to fatty acid), enzyme loading, and vacuum. Optimum conditions for synthesis of phytosteryl ester were a temperature of 60 °C, molar ratio of 1:4, enzyme loading of 10% (based on the total weight of the substrate), and pressure of 80 kPa. The maximum conversion of phytosteryl ester was ca. 93 mol % at the optimum condition.

Immobilization and characterisation of a lipase from a new source, Bacillus sp. ITP-001

A new source of lipase from Bacillus sp. ITP-001 was immobilized by physical adsorption on the polymer poly(3-hydroxybutyrate-co-hydroxyvalerate) (PHBV) in aqueous solution. The support and immobilized lipase were characterised, compared to the lyophilised lipase, with regard to the specific surface area, adsorption-desorption isotherms, pore volume (V(p)) and size (dp) by nitrogen adsorption, differential scanning calorimetry, thermogravimetric analysis, chemical composition analysis, Fourier transform infrared spectroscopy and biochemical properties. The immobilized enzyme displayed a shift in optimum pH towards the acidic side with an optimum at pH 4.0, whereas the optimum pH for the free enzyme was at pH 7.0; the optimum temperature of activity was 80 and 37 °C for the free and immobilized enzyme, respectively. The inactivation rate constant for the immobilized enzyme at 37 °C was 0.0038 h⁻¹ and the half-life was 182.41 h. The kinetic parameters obtained for the immobilized enzyme gave a Michaelis-Menten constant (K(m)) of 49.10 mM and a maximum reaction velocity (V(max)) of 205.03 U/g. Furthermore, the reuse of the lipase immobilized by adsorption allowed us to observe that it could be reused for 10 successive cycles, duration of each cycle (1 h), maintaining 33 % of the initial activity.

Immobilization of lipases on alkyl silane modified magnetic nanoparticles: effect of alkyl chain length on enzyme activity

Background

Biocatalytic processes often require a full recycling of biocatalysts to optimize economic benefits and minimize waste disposal. Immobilization of biocatalysts onto particulate carriers has been widely explored as an option to meet these requirements. However, surface properties often affect the amount of biocatalysts immobilized, their bioactivity and stability, hampering their wide applications. The aim of this work is to explore how immobilization of lipases onto magnetite nanoparticles affects their biocatalytic performance under carefully controlled surface modification.

Methodology/Principal Findings

Magnetite nanoparticles, prepared through a co-precipitation method, were coated with alkyl silanes of different alkyl chain lengths to modulate their surface hydrophobicity. Candida rugosa lipase was then directly immobilized onto the modified nanoparticles through hydrophobic interaction. Enzyme activity was assessed by catalytic hydrolysis of p-nitrophenyl acetate. The activity of immobilized lipases was found to increase with increasing chain length of the alkyl silane. Furthermore, the catalytic activities of lipases immobilized on trimethoxyl octadecyl silane (C18) modified Fe₃O₄ were a factor of 2 or more than the values reported from other surface immobilized systems. After 7 recycles, the activities of the lipases immobilized on C18 modified nanoparticles retained 65%, indicating significant enhancement of stability as well through hydrophobic interaction. Lipase immobilized magnetic nanoparticles facilitated easy separation and recycling with high activity retaining.

Conclusions/Significance

The activity of immobilized lipases increased with increasing alkyl chain length of the alkyl trimethoxy silanes used in the surface modification of magnetite nanoparticles. Lipase stability was also improved through hydrophobic interaction. Alkyl silane modified magnetite nanoparticles are thus highly attractive carriers for enzyme immobilization enabling efficient enzyme recovery and recycling.

Immobilization of Candida rugosa lipase on poly(3-hydroxybutyrate-co-hydroxyvalerate): a new eco-friendly support

The overall objective of this study is to evaluate the morphological [scanning electron microscopy (SEM)], physicochemical [differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), chemical composition analysis, Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR)], and biochemical properties of Candida rugosa lipase (CRL) immobilized on a natural biopolymer poly(3-hydroxybutyrate-co-hydroxyvalerate) (PHBV) in aqueous solution. CRL was immobilized by physical adsorption with efficiency of 30%. Compared with free CRL enzyme, there were slight changes in immobilized CRL activity as a function of temperature (from 37°C to 45°C), but a similar optimal pH value of 7.0. Inactivation rate constants for immobilized CRL enzyme were 0.009 and 0.334 h−1, and half-lives were 77 and 2 h at 40°C and 60°C, respectively. Kinetic parameters obtained for immobilized CRL include the Michaelis–Menten constant of K  m = 213.18 mM and maximum reaction velocity of V  max = 318.62 U/g. The operational stability of immobilized CRL was tested repeatedly, and after 12 cycles of reuse, the enzyme retained 50% activity. Based on our results, we propose that PHBV-immobilized CRL could serve as a promising biocatalyst in several industrial applications.

Microplate assay for aptamer-based thrombin detection using a DNA-enzyme conjugate based on histidine-tag chemistry

We report a method to prepare a DNA-enzyme conjugate using histidine-tag (His-tag) chemistry. A DNA oligonucleotide was modified with nitrilotriacetate (NTA), whose K(d) was approximately 10⁻⁶ (M⁻¹) toward a His-tag present on a recombinant protein via the complexation of Ni²⁺. His-tagged alkaline phosphatase (His-AP) was used as the model enzyme. Enzyme immobilization on the microplate revealed the conjugation of His-AP and the NTA-modified DNA via an Ni²⁺ complex. SPR measurements also proved the conjugation of His-AP with the NTA-modified DNA via an Ni²⁺ complex. The DNA-enzyme conjugate was then used for the detection of thrombin using a DNA aptamer. The DNA-AP conjugate successfully amplified the binding signal between the DNA aptamer and the thrombin, and the signal was measured as the fluorescent intensity derived from the AP-catalyzed reaction. The detection limit was 11 nM. Finally, we studied the effect of the release of the immobilized His-AP from the microplate on the AP activity, because the present strategy used a cleavable linker for the conjugation and the enzyme immobilization. The DNase-catalyzed release of the immobilized His-AP resulted in a 1.7-fold higher AP activity than observed when the His-AP was surface-immobilized.

Biochemical properties of free and immobilized Candida rugosa lipase onto Al2O3: a comparative study

Lipase from Candida rugosa (CRL) was immobilized by physical adsorption onto Al(2)O(3). The immobilization yield was more than 95% during 30 min. The properties of free and immobilized enzyme were also searched and compared. The optimum pH was shifted from 7 to 8.5 by immobilization of the enzyme. The maximum activity of the free and the immobilized enzymes occured at 35 and 40°C, respectively.

Properties of free and immobilized lipase from Pseudomonas cepacia

The purified lipase from Pseudomonas cepacia (PS, Amano) was immobilized on a commercially available microporous polypropylene support. The enzyme was rapidly and completely adsorbed on the support. Special attention was devoted to the demonstration of the lack of diffusional limitations, either internal or external, when a soluble substrate (p-nitrophenylacetate, pNPA) was used. The activity yield was high (100%) with pNPA and very low (0.4%) with p-nitrophenylpalmitate (pNPP). These values clearly showed that the immobilized enzyme was fully active as soon as activity was assayed on a soluble substrate rather than an insoluble one. With the latter one, the low activity was due mainly to a slow rate of substrate diffusion inside the porous support. The same diffusional phenomenon could explain the complete change of fatty acid specificity of the immobilized lipase. After immobilization, the lipase was mainly specific for short chain fatty acid esters, whereas the free enzyme was mainly specific for long chain esters. The activity-versus-temperature profiles were not greatly affected by immobilization with maximal reaction rates in the range 45 degrees to 50 degrees C for both enzyme preparations. However, immobilization increased enzyme stability mainly by decreasing the sensitivity to temperature of the inactivation reaction. Half-lives at 80 degrees C were 11 and 4 min for the immobilized and free enzymes, respectively. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 181-189, 1997.

Reactivity of Pure Candida rugosa Lipase Isoenzymes (Lip1, Lip2, and Lip3) in Aqueous and Organic Media. Influence of the Isoenzymatic Profile on the Lipase Performance in Organic Media

Three pure isoenzymes from Candida rugosa lipase (CRL: Lip1, Lip2, and Lip3) were compared in terms of their stability and reactivity in both aqueous and organic media. The combined effect of temperature and pH on their stability was studied applying a factorial design. The analysis of the response surfaces indicated that Lip1 and Lip3 have a similar stability, lower than that of Lip2. In aqueous media, Lip3 was the most active enzyme on the hydrolysis of p-nitrophenyl esters, whereas Lip1 showed the highest activity on the hydrolysis of most assayed triacylglycerides. The highest differences among isoenzymes were found in the hydrolysis of triacylglycerides. Thus, a short, medium, and long acyl chain triacylglyceride was the preferred substrate for Lip3, Lip1, and Lip2, respectively. In organic medium, Lip3 and Lip1 provided excellent results in terms of enantioselectivity in the resolution of ibuprofen (EF value over 0.90) and conversion, whereas initial esterification rate was higher for Lip3. However, the use of Lip2 resulted in lower values of conversion, enantiomeric excess, and enantioselectivity. In the case of trans-2-phenyl-1-cyclohexanol (TPCH) resolution, initial esterification rates were high except for Lip3, which also produced poor results in conversion and enantiomeric excess. The performance of the pure isoenzymes in the enantioselectivity esterification of these substrates was compared with different CRL crude preparations with known isoenzymatic content and the different results could not be explained by their isoenzymatic profile. Therefore, it can be concluded that other factors can also affect the catalysis of CRL and only the reproducibility between powders can ensure the reproducibility in synthesis reactions.

Exploiting the pressure effect on lipase-catalyzed wax ester synthesis in dense carbon dioxide

The present work focuses on the thermodynamic interpretation of the lauryl oleate biosynthesis in high-pressure carbon dioxide. Lipase-catalyzed lauryl oleate production by oleic acid esterification with 1-dodecanol over immobilized lipase from Rhizomucor miehei (Lipozyme RM IM) was successfully performed in a sapphire window batch stirred tank reactor (BSTR) using dense CO(2) as reaction medium. The experiments were planned to elucidate the pressure effect on the reaction performance. With increasing the pressure up to 10 MPa, the catalytic efficiency of the studied enzyme improved rising up to a maximum and decreased at higher pressure values. Kinetic observations, exhibiting that dense CO(2) expanded reaction mixture in subcritical conditions led to higher performance than when diluted in a single supercritical phase, were elucidated by phase-equilibrium arguments. The experimental results were justified with emphasis on thermodynamic interpretation of the studied system. Particularly, the different reaction performances obtained were related to the position of the operating point with respect to the location of liquid-vapor phase boundaries of the reactant fatty acid/alcohol/CO(2) ternary system. The outlook for exploitation of CO(2) expanded phase at lower pressure compared to supercritical phase, with heterogeneous system in which the solid catalyst particles are exposed to dense CO(2) expanded reaction mixture, in developing new biotransformation schemes is promising.

Immobilization of lipase onto micron-size magnetic beads

A novel and economical magnetic poly(methacrylate-divinylbenzene) microsphere (less than 8 microm in diameter) was synthesized by the modified suspension polymerization of methacrylate and cross-linker divinylbenzene in the presence of magnetic fluid. Then, surface aminolysis was employed to obtain a high content of surface amino groups (0.40-0.55 mmolg(-1) supports). The morphology and properties of these magnetic supports were characterized with scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and a vibrating sample magnetometer. These magnetic supports exhibited superparamagnetism with a high specific saturation magnetization (sigma(s)) of 14.6 emicrog(-1). Candida cylindracea lipase was covalently immobilized on the amino-functionalized magnetic supports with the activity recovery up to 72.4% and enzyme loading of 34.0 mgg(-1) support, remarkably higher than the previous studies. The factors involved in the activity recovery and enzymatic properties of the immobilized lipase prepared were studied in comparison with free lipase, for which olive oil was chosen as the substrate. The results show that the immobilized lipase has good stability and reusability after recovery by magnetic separation within 20s.

Optimization of adsorptive immobilization of alcohol dehydrogenases

In this work, a systematic examination of various parameters of adsorptive immobilization of alcohol dehydrogenases (ADHs) on solid support is performed and the impact of these parameters on immobilization efficiency is studied. Depending on the source of the enzymes, these parameters differently influence the immobilization efficiency, expressed in terms of residual activity and protein loading. Residual activity of 79% was achieved with ADH from bakers' yeast (YADH) after optimizing the immobilization parameters. A step-wise drying process has been found to be more effective than one-step drying. A hypothesis of deactivation through bubble nucleation during drying of the enzyme/glass bead suspension at low drying pressure (<45 kPa) is experimentally verified. In the case of ADH from Lactobacillus brevis (LBADH), >300% residual activity was found after drying. Hyperactivation of the enzyme is probably caused by structural changes in the enzyme molecule during the drying process. ADH from Thermoanaerobacter species (ADH T) is found to be stable under drying conditions (>15 kPa) in contrast to LBADH and YADH.

Single-step purification of lipase from Burkholderia multivorans using polypropylene matrix

Lipase from Burkholderia multivorans was purified with high yields directly from fermentation broth by a single-step purification protocol involving adsorption and desorption. The crude enzyme (lyophilized powder) from B. multivorans was loaded on Accurel (Membrana, Germany), a polypropylene matrix, using butanol as the solvent in a buffer at pH 9.0 and ambient temperature for a period of 12 h. The enzyme adsorbed onto the matrix with high specific activity (33 units mg(-1) protein). This was followed by desorption of the enzyme from the matrix using Triton X-100 as the eluent. The enzyme was finally recovered by precipitation with acetone (50%, v/v). Thus, an overall enzyme yield of 66% with a 3.0-fold purification was obtained. The purity of the enzyme was ascertained by SDS-PAGE. The phenomenon of adsorption and desorption on Accurel was studied for three more lipases, viz. Mucor meihei lipase (Sigma-Aldrich Co.), Lipolase (Novo Nordisk, Denmark) and Pseudomonas aeruginosa lipase (laboratory isolate).

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 %.

Adsorption and Activity of Candida rugosa Lipase on Polypropylene Hollow Fiber Membrane Modified with Phospholipid Analogous Polymers

Efforts have recently been made toward the study of interactions of phospholipid with various enzymes. It seems that phospholipids may be directly involved in regulating the enzyme activity. In this work, three phospholipid analogous polymers (PAPs), containing hydrophobic octyloxy, dodecyloxy, and octadecyloxy groups (abbreviated as 8-PAP, 12-PAP, and 18-PAP, respectively), were tethered on polypropylene hollow fiber microfiltration membrane (PPHFMM) to create a biocompatible interface for lipase immobilization. Lipase from Candida rugosa was immobilized on these PPHFMMs by adsorption. The adsorption capacity, activity, and thermal stability of enzyme on the PAP-modified PPHFMMs were compared with those of enzyme on the nascent ones. It was found that, as for the PAP-modified PPHFMMs, the adsorption capacities of lipase are lower than that of the nascent ones, while the activity retention of immobilized lipase increases from 57.5% to 74.1%, 77.5%, and 83.2% respectively for the 8-PAP-, 12-PAP-, and 18-PAP-modified PPHFMMs. In addition, the experimental results of thermal stability show that the residual activity of the immobilized lipase at 50 degrees C for 2 h is 62% for the 8-PAP-modified PPHFMM, 59% for the 12-PAP-modified PPHFMM, and 66% for the 18-PAP-modified PPHFMM, which are also higher than that of the nascent ones.