Blueprint for a lipase support: Use of hydrophobic controlled-pore glasses as model systems

Ethanol as additive enhance the performance of immobilized lipase LipA from Pseudomonas aeruginosa on polypropylene support

Immobilization is practical to upgrade enzymes, increasing their performance and expanding their applications. The recombinant, solvent tolerant lipase LipA PSA01 from Pseudomonas aeruginosa was immobilized on polypropylene Accurel® MP1004 to improve its performance. We investigated the effect of ethanol as an additive during the immobilization process at three concentrations (20%, 25%, and 30%) on the operational behavior of the enzyme. The immobilization efficiency was higher than 92%, and the immobilized enzymes showed hyperactivation and thermal resistance depending on the concentration of ethanol. For example, at 70 °C, the free enzyme lost the activity, while the prepared one with ethanol 25% conserved a residual activity of up to 73.3% (∆ T¹⁵ ₅₀ = 27.1 °C). LipA immobilized had an optimal pH value lower than that of the free enzyme, and the organic solvent tolerance of the immobilized enzymes depended on the ethanol used. Hence, the immobilized enzyme with ethanol 25% showed hyperactivation to more solvents than the soluble enzyme. Remarkable stability towards methanol (up to 8 folds) was evidenced in all the immobilized preparations. The immobilized enzyme changed their chemo preference, and it hydrolyzed oils preferentially with short-chain than those with long-chain. LipA had a notable shelf-life after one year, keeping its activity up to 87%. Ethanol facilitated the access of the enzyme to the hydrophobic support and increased its activity and stability according to the amount of ethanol added.

Optimization of physical parameters for enhanced production of lipase from Staphylococcus hominis using response surface methodology

Lipase, a versatile hydrolytic enzyme, is gaining more importance in environmental applications such as treatment of oil and grease containing wastewater, pretreatment of solid waste/industrial wastewater for anaerobic treatment. In the present study, the attempts have been made to improve the production of lipase from Staphylococcus hominis MTCC 8980 by optimization of pH, temperature, and agitation speed in lab scale shake flasks culture. The experiments were designed using the full factorial central composite design of experiment. A total of 20 experiments were conducted, and the optimized pH, temperature, and agitation speed were found to be 7.9, 33.1 °C, and 178.4 rpm, respectively. The results of the analysis of variance (ANOVA) test revealed that the linear terms for temperature and agitation were significant (p value < 0.05). Interaction for pH and agitation speed was found to have a significant effect on lipase production from S. hominis MTCC 8980. A 150% increase in enzyme activity was observed under the optimized conditions with the maximum lipase activity of 1.82 U/ml. Further enhancement of enzyme activity can be expected from the optimization of medium components.

Characterization of non-covalent immobilized Candida antartica lipase b over PS-b-P4VP as a model bio-reactive porous interface

The design of interfaces that selectively react with molecules to transform them into compounds of industrial interest is an emerging area of research. An example of such reactions is the hydrolytic conversion of ester-based molecules to lipids and alcohols, which is of interest to the food, and pharmaceutical industries. In this study, a functional bio-interfaced layer was designed to hydrolyze 4-nitrophenyl acetate (pNPA) and Ricinus Communis (castor) oil rich in triglycerides using lipase b from Candida antarctica (CALB, EC 3.1.1.3). The attachment of CALB was performed via non-covalent immobilization over a polymer film of vertically aligned cylinders that resulted from the self-assembly of the di-block copolymer polystyrene-block-poly(4-vinyl pyridine) (PS-b-P4VP). This polymer-lipase model will serve as the groundwork for the design of further bioactive layers for separation applications requiring similar hydrolytic processes. Results from the fabricated functional bio-interfaced material include cylinders with featured pore size of 19 nm, d spacing of 34 nm, and ca. 40 nm of thickness. The polymer-enzyme layers were physically characterized using AFM, XPS, and FTIR. The immobilized enzyme was able to retain 91% of the initial enzymatic activity when using 4-nitrophenyl acetate (pNPA) and 78% when exposed to triglycerides from castor oil.

Rational Design Strategy as a Novel Immobilization Methodology Applied to Lipases and Phospholipases

Immobilization of lipases and phospholipases, mainly on water-insoluble carriers, helps in their economic reusing and in the development of continuous bioprocesses. Design of efficient lipase and phospholipase-immobilized systems is rather a difficult task. A lot of research work has been done in order to optimize immobilization techniques and procedures and to develop efficient immobilized systems. We conceived a new strategy for the rational design of immobilized derivatives (RDID) in favor of the successful synthesis of optimal lipase and phospholipase-immobilized derivatives, aiming the prediction of the immobilized derivative's functionality and the optimization of load studies. The RDID strategy begins with the knowledge of structural and functional features of synthesis components (protein and carrier) and the practical goal of the immobilized product. The RDID strategy was implemented in a software named RDID_1.0. The employment of RDID allows selecting the most appropriate way to prepare immobilized derivatives more efficient in enzymatic bioconversion processes and racemic mixture resolution.

Macroporous Beads for Lipase Immobilization

Lipase isolated from Arthrobacter sp. (RRLJ-1, MTCC No. 5125, named ABL), is effective in resolving a wide range of racemic drug intermediates. In this study, ABL was immobilized on a series of synthetic macroporous epoxy copolymers beads with varying pore sizes, surface area and hydrophobicity. Poly(glycidyl methacrylate-co-ethylene dimethacrylate) beads, with 75% crosslink density and 10% of epoxy groups modified with dibutyl amine [GMA-EGDM-75 (10% DBA)] had a pore volume of 0.77 mL/g and a surface area of 86.05 m 2/g; these beads were optimally suitable for ABL immobilization. The covalent binding of the lipase was optimized by varying the ionic strength, buffers, pH, temperature and time. The optimal binding was achieved in 100 mM phosphate buffer at 4°C, pH 7.0 in three hours. Under these conditions the polymer retained 34 units and 12 mg of ABL per gram. Immobilized ABL displayed enhanced thermal, organic solvent and pH stability compared to the free enzyme. The immobilized enzyme was used repeatedly (fifteen cycles) to resolve the fluoxitine intermediate (racemic ethyl-3-hydroxy-3-phenyl propanoate) without any loss in stereospecificity. The resolution time of fluoxitine intermediate was reduced to almost half (from 84 to 48 hours) by using the immobilized enzyme.

Rational design of immobilized lipases and phospholipases

Immobilization of lipases and phospholipases on, mainly, water insoluble carriers, helps in their economic reuse and in the development of continuous bioprocesses. Design of efficient lipases and phospholipases-immobilized system is rather a difficult task. A lot of research work has been done in order to optimize immobilization techniques and procedures and to develop an efficient immobilized system. A new rational design of immobilized derivatives strategy (RDID) has been conceived in favor of the successful synthesis of optimal lipases and phospholipases-immobilized derivatives, aiming prediction of the immobilized derivative's functionality and the optimization of load studies. RDID begins with the knowledge of structural and functional features of synthesis components (protein and carrier), and the practical goal of immobilized product. RDID was implemented in software named RDID ( 1.0 ). The employment of RDID allows selecting the most appropriate way to prepare immobilized derivatives more efficient in enzymatic bioconversion processes and racemic mixture resolution.

Overview of fungal lipase: a review

Lipases (triacylglycerolacyl hydrolases, EC3.1.1.3) are class of enzymes which catalyze the hydrolysis of long-chain triglycerides. In this review paper, an overview regarding the fungal lipase production, purification, and application is discussed. The review describes various industrial applications of lipase in pulp and paper, food, detergent, and textile industries. Some important lipase-producing fungal genera include Aspergillus, Penicillium, Rhizopus, Candida, etc. Current fermentation process techniques such as batch, fed-batch, and continuous mode of lipase production in submerged and solid-state fermentations are discussed in details. The purification of lipase by hydrophobic interaction chromatography is also discussed. The development of mathematical models applied to lipase production is discussed with special emphasis on lipase engineering.

Pore-Size Tunable Mesoporous Zirconium Organophosphonates with Chiral l-Proline for Enzyme Adsorption

Mesoporous zirconium organophosphonates with a tunable mesopore (pore diameter: from 4.8 to 16.3 nm) were synthesized through co-condensation of ZrCl4 and 1-phosphomethylproline (H3PMP) with the aid of organic additives in the presence of an anionic surfactant (sodium dodecyl sulfate) under weak acidic conditions. The organic additives, tetrahydrofuran, can effectively strengthen the assembly of ZrCl4 and H3PMP around the surfactant micelles through decreasing the hydrolysis and condensation rate of ZrCl4. The results of the N2 sorption isotherm and SEM image show that zirconium phosphate with a bimodal structure is formed by calcination of mesoporous zirconium organophosphonate. Mesoporous zirconium organophosphonates can effectively adsorb lysozyme (Lz) and papain, and the adsorption equilibrium for Lz can be reached within 30 min. The adsorption capacity for Lz and papain can reach as high as 438 and 297 mg/g, respectively. Furthermore, Lz adsorbed on mesoporous zirconium organophosphonates can retain its structural conformation as in its free state, and no leaching of Lz from the solid was observed when shaking the Lz-loaded solid in a buffer solution. Also, the existence of L-proline in the mesopore could help the adsorption of papain at a pH value lower than the pI of papain.

Combinatorial Discovery of Reusable Noncovalent Supports for Enzyme Immobilization and Nonaqueous Catalysis

A simple and effective method is described for the preparation of enzyme-containing materials that possess excellent catalytic activity, mechanical strength, and reusability. Uniform spherical beads were produced via the colyophilization of alpha-chymotrypsin with the support materials, leaving the active enzyme entrapped within the porous "ice-templated" support matrix. The composites were assayed for catalytic activity by monitoring a nonaqueous transesterification reaction. The mechanical strength for each composite was measured using a compression assay. Initial screens identified a set of six support materials that contributed favorably to either the enzyme activity or to the mechanical strength of the composite. A design of experiments (DoE) methodology was employed to screen 80 combinations of these six "base" materials. A model representing this formulation space was constructed which could be used to predict both the catalytic activity and mechanical strength with reasonable accuracy for any combination of the six base component materials. This model was used to predict optimized materials with an enzyme activity that was 50 times greater than that of the free enzyme. The model was also used to set a minimum acceptable mechanical stability for these composites, and the resulting materials were shown to be reusable for at least ten reaction cycles.

Immobilization of Pancreatic Lipase on Chitin and Chitosan

In this study, porcine pancreatic lipase (EC 3.1.1.3) was immobilized on chitin and chitosan by adsorption and subsequent crosslinking with glutaraldehyde, which was added before (conjugation) or after (crosslinking) washing unbound proteins. Conjugation proved to be the better method for both supports. The properties of free and immobilized enzymes were also investigated and compared. The results showed that the pH optimum was shifted from 8.5 to 9.0 for both the immobilized enzymes. Also, the optimum temperature was shifted from 30 to 40 degrees C for chitin-enzyme and to 45 degrees C for chitosan-enzyme conjugates. The immobilization efficiency is low, but the immobilized enzymes have good reusability and stability (storage and operational). Besides these properties, the immobilized lipases were also suitable for catalyzing esterification reactions of fatty acids and fatty alcohols, both with a medium chain length. According to our results, esterification activities of immobilized lipases were two- and four-fold higher for chitosan- and chitin-enzyme, than for the free enzyme, respectively. The immobilization procedure shows a great potential for commercial applications of the immobilized lipase, a relatively low cost commercial enzyme.

Production, purification, characterization, and applications of lipases

Lipases (triacylglycerol acylhydrolases, EC 3.1.1.3) catalyze the hydrolysis and the synthesis of esters formed from glycerol and long-chain fatty acids. Lipases occur widely in nature, but only microbial lipases are commercially significant. The many applications of lipases include speciality organic syntheses, hydrolysis of fats and oils, modification of fats, flavor enhancement in food processing, resolution of racemic mixtures, and chemical analyses. This article discusses the production, recovery, and use of microbial lipases. Issues of enzyme kinetics, thermostability, and bioactivity are addressed. Production of recombinant lipases is detailed. Immobilized preparations of lipases are discussed. In view of the increasing understanding of lipases and their many applications in high-value syntheses and as bulk enzymes, these enzymes are having an increasing impact on bioprocessing.

Imaging the distribution and secondary structure of immobilized enzymes using infrared microspectroscopy

Synchrotron infrared microspectroscopy (SIRMS) was used for the first time to image the distribution and secondary structure of an enzyme (lipase B from Candida antarctica, CALB) immobilized within a macroporous polymer matrix (poly(methyl methacrylate)) at 10 microm resolution. The beads of this catalyst (Novozyme435) were cut into thin sections (12 microm). SIRMS imaging of these thin sections revealed that the enzyme is localized in an external shell of the bead with a thickness of 80-100 microm. Also, the enzyme was unevenly distributed throughout this shell. Furthermore, by SIRMS-generated spectra, it was found that CALB secondary structure was not altered by immobilization. Unlike CALB, polystyrene molecules of similar molecular weight diffuse easily throughout Novozyme435 beads. Scanning electron micrograph (SEM) images of the Novozyme435 beads showed that the average pore size is 10 times larger than CALB or polystyrene molecules, implying that there is no physical barrier to enzyme or substrate diffusion throughout the bead. Thus, the difference between polystyrene and enzyme diffusivity suggests that protein-matrix and protein-protein interactions govern the distribution of the enzyme within the macroporous resin.

Sol-gel immobilization of serine proteases for application in organic solvents

The serine proteases alpha-chymotrypsin, trypsin, and subtilisin Carlsberg were immobilized in a sol-gel matrix and the effects on the enzyme activity in organic media are evaluated. The percentage of immobilized enzyme is 90% in the case of alpha-chymotrypsin and the resulting specific enzyme activity in the transesterification of N-acetyl-L-phenylalanine ethyl ester with 1-propanol in cyclohexane is 43 times higher than that of a nonimmobilized lyophilized alpha-chymotrypsin. The activities of trypsin and subtilisin Carlsberg are enhanced with 437 and 31 times, respectively. The effect of immobilization on the enzyme activity is highest in hydrophobic solvents.

Phage display combinatorial libraries of short peptides: ligand selection for protein purification

A library of heptapeptides displayed on the surface of filamentous phage M13 was evaluated as a potential source of affinity ligands for the purification of Rhizomucor miehei lipase. Two independent selection (biopanning) protocols were employed: the enzyme was either physically adsorbed on polystyrene or chemically immobilized on small magnetic beads. From screening with the polystyrene-adsorbed lipase it was found that there was a rapid enrichment of the library with "doublet" clones i.e. the phage species which carried two consecutive sequences of heptapeptides, whilst no such clones were observed from the screening using lipase attached to magnetic beads. The binding of the best clones to the enzyme was unambiguously confirmed by ELISA. However the synthetic heptapeptide of identical sequence to the best "monomeric" clone did not act as a satisfactory affinity ligand after immobilization on Sepharose. This indicated that the interaction with lipase was due to both the heptapeptide and the presence of a part of the phage coat protein. This conclusion was further verified by immobilizing the whole phage on the surface of magnetic beads and using the resulting conjugate as an affinity adsorbent. The scope of application of this methodology and the possibility of preparing phage-based affinity materials are briefly discussed.

A new method for the generation of patterned protein films by encapsulation in arrays of thermally evaporated lipids

In this article we demonstrate a versatile method for the generation of patterned protein films by encapsulation in arrays of the lipids, octadecylamine (ODA, cationic), and arachidic acid (AA, anionic). A simple 2 x 2 array of ODA and AA was vacuum deposited on different substrates using appropriate masks. Thereafter, the enzymes pepsin and fungal protease as well as the heme-proteins cytochrome c and hemoglobin were encapsulated in the different elements of the array by sequential immersion (combined with judicious masking) of the array elements in the different protein solutions. The proteins are incorporated into the lipid elements by electrostatic interaction between charged amino acid residues on the protein surface and charged functional groups in the lipid matrix. This procedure leads to spatially distinct regions of the different proteins on one substrate and shows promise for single-chip multianalyte immunoassay/multiplex, high-throughput biosensor and catalysis applications. Fourier transform infrared spectroscopy (FTIR) was used to monitor the incorporation of the proteins in the different elements of the array as well as to ascertain whether intermixing of the proteins in a particular array element had occurred. The heme-protein composite regions were further characterized using UV-VIS spectroscopy.

Fabrication, characterization, and enzymatic activity of encapsulated fungal protease--fatty lipid biocomposite films

Encapsulation of an aspartic protease from the fungus Aspergillus saitoi (F-prot) in thermally evaporated fatty acid films by a simple beaker-based immersion technique under enzyme-friendly conditions is described. The approach is based on diffusion of the enzyme from aqueous solution, driven primarily by attractive electrostatic interaction between charged groups on the enzyme surface and ionized lipid molecules in the film. The encapsulated enzyme molecules could be "pumped out" of the biocomposite film into solution by modulating the electrostatic interaction between the enzyme and fatty acid molecules via solution pH variation. The kinetics of F-prot diffusion into the acid films was followed using quartz crystal microgravimetry measurements while the secondary and tertiary structure of the enzyme in the lipid matrix was studied using Fourier transform infrared (FT-IR) and fluorescence spectroscopies. FT-IR and fluorescence measurements indicated little perturbation to the native structure of the enzyme. A chemical analysis of the F-prot-fatty acid biocomposite film was also performed using X-ray photoelectron spectroscopy. The encapsulated F-prot molecules showed catalytic activity (as estimated by reaction with hemoglobin) comparable to free enzyme molecules in solution, indicating facile access of biological analytes/reactants in solution to the enzyme molecules. The advantages/disadvantages of this approach vis-à-vis methods currently used for encapsulation of biomolecules are briefly discussed.