Immobilization of Candida rugosa lipase on poly(allyl glycidyl ether-co-ethylene glycol dimethacrylate) macroporous polymer particles

Cutinases as stereoselective catalysts: Specific activity and enantioselectivity of cutinases and lipases for menthol and its analogs

The specific activity and enantioselectivity of immobilized cutinases from Aspergillus oryzae (AoC) and Humicola insolens (HiC) were compared with those of lipases from Thermomyces lanuginosus (TLL), Rhizomucor miehei (RML) and Lipase B from Candida antarctica (CALB) for menthol and its analogs that include isopulegol, trans-2-tert-butylcyclohexanol (2TBC), and dihydrocarveol (DHC). Common features of these alcohols are two bulky substituents: a cyclohexyl ring and an alkyl substituent. Dissimilarities are that the alkyl group reside at different positions or have dissimilar structures. The aim was to develop an understanding at a molecular level of similarities and differences in the catalytic behavior of the selected cutinases and lipases as a function of substrate structural elements. The experimental results reflect the (-)-enantioselectivity for AoC, HiC, TLL, and RML, while CALB is only active on DHC with (+)-enantioselectivity. In most cases, AoC has the highest activity while HiC is significantly more active than other enzymes on 2TBC. The E values of AoC, HiC, TLL, and RML for menthol are 27.8, 16.5, 155, and 125, respectively. HiC has a higher activity (>10-fold) on (-)-2TBC than AoC while they exhibit similar activities on menthol. Docking results reveal that the bulky group adjacent to the hydroxyl group determines the enantioselectivity of AoC, HiC, TLL, and RML. Amino acid residues that dominate the enantioselectivity of these enzymes are AoC's Phe195 aromatic ring; HiC's hydrophobic Leu 174 and Ile 169 groups; TLL's ring structures of Trp89, His258 and Tyr21; and Trp88 for RML. Results of this study highlight that cutinases can provide important advantages relative to lipases for enantioselective transformation, most notably with bulky and sterically hindered substrates.

Sensitive impedimetric biosensor for direct detection of diazinon based on lipases

Two novel impedimetric biosensors for highly sensitive and rapid quantitative detection of diazinon in aqueous medium were developed using two types of lipase, from Candida Rugosa (microbial source) (CRL) and from porcine pancreas (animal source) (PPL) immobilized on functionalized gold electrode. Lipase is characterized to specifically catalyze the hydrolysis of ester functions leading to the transformation of diazinon into diethyl phosphorothioic acid (DETP) and 2-isopropyl-4-methyl-6-hydroxypyrimidine (IMHP). The developed biosensors both presented a wide range of linearity up to 50 μM with a detection limit of 10 nM for Candida Rugosa biosensor and 0.1 μM for porcine pancreas biosensor. A comparative study was carried out between the two biosensors and results showed higher efficiency of Candida Rugosa sensor. Moreover, it presented good accuracy and reproducibility, had very good storage and multiple use stability for 25 days when stored at 4°C.

Parameters Affecting the Performance of Immobilized Enzyme

Enzyme immobilization has been investigated to improve lipase properties over the past few decades. Different methods and various carriers have been employed to immobilize enzyme. However, the application of enzymatic technology in large scale is rarely seen during the industrial process. The main obstacles are a high cost of the immobilization and the poor performance of immobilized lipase. This review focuses on the current status of enzyme immobilization, which aims to summarize the latest research on the parameters affecting the performance of immobilized enzyme. Particularly, the effect of immobilization methods, immobilization carriers, and enzyme loading has been discussed.

Optimal Conditions for Continuous Immobilization of Pseudozyma hubeiensis (Strain HB85A) Lipase by Adsorption in a Packed-Bed Reactor by Response Surface Methodology

This study aimed to develop an optimal continuous process for lipase immobilization in a bed reactor in order to investigate the possibility of large-scale production. An extracellular lipase of Pseudozyma hubeiensis (strain HB85A) was immobilized by adsorption onto a polystyrene-divinylbenzene support. Furthermore, response surface methodology (RSM) was employed to optimize enzyme immobilization and evaluate the optimum temperature and pH for free and immobilized enzyme. The optimal immobilization conditions observed were 150 min incubation time, pH 4.76, and an enzyme/support ratio of 1282 U/g support. Optimal activity temperature for free and immobilized enzyme was found to be 68°C and 52°C, respectively. Optimal activity pH for free and immobilized lipase was pH 4.6 and 6.0, respectively. Lipase immobilization resulted in improved enzyme stability in the presence of nonionic detergents, at high temperatures, at acidic and neutral pH, and at high concentrations of organic solvents such as 2-propanol, methanol, and acetone.

Preparation and characterization of monodispersed microfloccules of TiO₂ nanoparticles with immobilized multienzymes

Microfloccules of TiO(2) nanoparticles, on which glycerol-dehydrogenase (GDH), 1,3-propanediol-oxidoreductase (PDOR), and glycerol-dehydratase (GDHt) were coimmobilized, were prepared by adsorption-flocculation with polyacrylamide (PAM). The catalytic activity of immobilized enzyme in the glycerol redox reaction system, the enzyme leakage, stabilities of pH and temperature, as well as catalytic kinetics of immobilized enzymes relative to the free enzymes were evaluated. Enzyme loading on the microfloccules as much as 104.1 mg/g TiO(2) (>90% loading efficiency) was obtained under the optimal conditions. PAM played a key role for the formation of microfloccules with relatively homogeneous distribution of size and reducing the enzyme leakage from the microfloccules during the catalysis reaction. The stabilities of GDH against pH and temperature was significantly higher than that those of free GDH. Kinetic study demonstrated that simultaneous NAD(H) regeneration was feasible in glycerol redox system catalysted by these multienzyme microfloccules and the yield of 1, 3-popanediol (1, 3-PD) was up to 11.62 g/L. These results indicated that the porous and easy-separation microfloccules of TiO(2) nanoparticles with immobilized multienzymes were efficient in term of catalytic activity as much as the free enzymes. Moreover, compared with free enzyme, the immobilized multienzymes system exhibited the broader pH, higher temperature stability.

Improvement of catalytic activity of lipase from Candida rugosa via sol-gel encapsulation in the presence of calix(aza)crown

Lipase from Candida rugosa (CRL) was encapsulated within a chemically inert sol-gel support in the presence of calix(aza)crowns as the new additives. The catalytic activity of the encapsulated lipases was evaluated both in the hydrolysis of p-nitrophenyl palmitate (p-NPP) and the enantioselective hydrolysis of racemic Naproxen methyl ester. It has been observed that the percent activity yields of the calix(aza)crown based encapsulated lipases were higher than that of the free lipase. Improved enantioselectivity was observed with the calix(aza)crown-based encapsulated lipases as compared to encapsulated free lipase. The reaction of Naproxen methyl ester resulted in 48.4% conversion for 24h and 98% enantiomeric excess for the S-acid, corresponding to an E value of >300 (E=166 for the encapsulated free enzyme). Moreover, the encapsulated lipases were still retained about 18% of their conversion ratios after the sixth reuse in the enantioselective reaction.

Effect of solvents and precipitant on the properties of chitosan nanoparticles in a water-in-oil microemulsion and its lipase immobilization performance

When chitosan nanoparticles were prepared in a water-in-oil (W/O) microemulsion by using 2% (wt) acetic acid (HAc) and 30% (wt) tri-n-octylamine (TOA) as solvent and precipitant, respectively, particle diameters of 7 nm were observed and the particles formed ovoid shaped aggregates. Using 0.05% HCl and 5.0M NaOH as solvent and precipitant produced nanoparticles 10nm in size that aggregated in the form of snowflakes. These two types of nanoparticles were used to immobilize lipase, the lipase adsorption capacity using nanoparticles 7 nm in size reached 156 mg/g and activity retention compared to free enzyme was as high as 66.7%, and the residual activity of the immobilized lipase was 91% after 5 runs of reaction. In additional, the activity retention of nanoparticles 10nm in size also could reach 62.8%. This indicated that the chitosan nanoparticles prepared in a W/O microemulsion were suitable for lipase immobilization.

Adsorption induced enzyme denaturation: the role of polymer hydrophobicity in adsorption and denaturation of alpha-chymotrypsin on allyl glycidyl ether (AGE)-ethylene glycol dimethacrylate (EGDM) copolymers

Effects of changes in hydrophobicity of polymeric support on structure and activity of alpha-chymotrypsin (E.C. 3.4.21.1) have been studied with copolymers of allyl glycidyl ether (AGE) and ethylene glycol dimethacrylate (EGDM) with increasing molar ratio of EGDM to AGE (cross-link density 0.05 to 1.5). The enzyme is readily adsorbed from aqueous buffer at room temperature following Langmuir adsorption isotherms in unexpectedly large amounts (25% w/w). Relative hydrophobicity of the copolymers has been assessed by studying adsorption of naphthalene and Fmoc-methionine by the series of copolymers from aqueous solutions. Polymer hydrophobicity appears to increase linearly on increasing cross-link density from 0.05 to 0.25. Further increase in cross-link density causes a decrease in naphthalene binding but has little effect on binding of Fmoc-Met. Binding of alpha-chymotrypsin to these copolymers follow the trend for Fmoc-methionine binding, rather than naphthalene binding, indicating involvement of polar interactions along with hydrophobic interactions during binding of protein to the polymer. The adsorbed enzyme undergoes extensive denaturation (ca. 80%) with loss of both tertiary and secondary structure on contact with the copolymers as revealed by fluorescence, CD and Raman spectra of the adsorbed protein. Comparison of enzyme adsorption behavior with Eupergit C, macroporous Amberlite XAD-2, and XAD-7 suggests that polar interactions of the EGDM ester functional groups with the protein play a significant role in enzyme denaturation.

Immobilization of Candida rugosa lipase on sporopollenin from Lycopodium clavatum

Sporopollenin is a natural polymer obtained from Lycopodium clavatum, which is highly stable with constant chemical structure and has high resistant capacity to chemical attack. In this study, immobilization of lipase from Candida rugosa (CRL) on sporopollenin by adsorption method is reported for the first time. Besides this, the enzyme adsorption capacity, activity and thermal stability of immobilized enzyme have also been investigated. It has been observed that under the optimum conditions (Spo-E((0.3))), the specific activity of the immobilized lipase on the sporopollenin by adsorption was 16.3U/mg protein, which is 0.46 times less than that of the free lipase (35.6U/mg protein). The pH and temperature of immobilized enzyme were optimized, which were 6.0 and 40 degrees C respectively. Kinetic parameters V(max) and K(m) were also determined for the immobilized lipase. It was observed that there is an increase of the K(m) value (7.54mM) and a decrease of the V(max) value (145.0U/mg-protein) comparing with that of the free lipase.