Papers by Keyword: Lipase

Abstract: The structure of Candida rugosa lipase can be affected by solvents used in the enzymatic reactions. Using molecular dynamics simulation as a tool to study the Candida rugosa lipase structure, we studied the effect of various solvent systems, such as water, water-methanol, and water-methanol-ionic liquid. These solvent systems have been chosen because lipase is able to function in both aqueous and non-aqueous medium. In this study, pyridinium (Py)-based ionic liquids were selected as co-solvent. The MD simulation was run for 50 nanoseconds for each solvent system at 328 K. In the case of water-methanol-ionic liquids solvent systems, the total number of the ionic liquids added were varied: 222, 444, and 888 molecules. Water was used as the reference solvent system. The structure of Candida rugosa lipase in water-methanol system significantly changed from the initial structure as indicated by the RMSD value, which was about 6.4 Å after 50 ns simulation. This value was relatively higher compared to the other water-methanol solvent system containing ionic liquid as co-solvent, which were 2.43 Å for 4Py-Br, 2.1 Å for 8Py-Br, 3.37 Å for 4Py-BF₄ and 3.49 Å for 8Py-BF₄ respectively. Further analysis by calculating the root mean square fluctuation (RMSF) of each lipase residue found that the presence of ionic liquids could reduce changes in the enzyme structure. This happened because the anion component of the ionic liquid interacts relatively more strongly with residues on the surface of the protein as compared to methanol, thereby lowering the possibility of methanol to come into contact with the protein.

Abstract: Nowadays the development of biodiesel production as an alternative renewable energy became crucial. The reusability of enzymes as biocatalysts in biodiesel production has limitations and can be improved by the immobilization process onto the appropriate solid support, such as polyethersulfone (PES). Polyethersulfone has been synthesized utilizing microwave-assisted reaction method (400 W, 170 °C, 60 minutes). Nitration reaction of PES was performed by refluxing the synthesized PES with the mixtures of H₂SO₄ (0 °C, ± 30 minutes) and HNO₃ (25 °C, 4 hours). The –NO₂ groups of the synthesized PES-NO₂ was subsequently reduced to be PES-NH₂ using SnCl₂.2H₂O as reducing agent by reflux method (60 °C, ± 3 hours). The structure of PES and its derivatives was confirmed by FTIR and ¹H-NMR. Candida antarctica lipase was successfully immobilized onto the synthesized PES and its derivatives, which were confirmed by its FTIR spectra and its activity tests of the supernatants in hydrolyzing p-nitrophenol palmitate (pNPP) into p-nitrophenol (pNP). The results showed that the conversion percentage of pNPP to become pNP were 20.6% (free enzyme), 18.9% (PES-enzyme), and 3.7% (PES-NH₂-enzyme). The decrease in the supernatant enzyme activity showed that the enzyme has been successfully immobilized through physical adsorption onto the synthesized polymers.

Abstract: Alcaligenes sp. JG3 is a local strain bacterium from Indonesia, isolated from cultivated corn field of Central Java. This bacterium is able to produce lipase with fairly high activity. In order to do lipase gene sequence characterization, two sets of primer pair were used in this study (primer Fjg3 5’- ATGACCGAGCTGACTGTAG-3’, Rjg3 5’-TCAGGAGGGGTAAATCCAC-3’ and internal primer Fi 5’-TGACCCATGACCAGGCGGAA-3’ and Ri 5’-TTCGCCTGGTCATGGGTCA-3’). The complete lipase JG3 gene sequence consists of 1081 bp from start codon ATG to the stop codon of TGA. Lipase JG3 had high similarity to another lipase from genus Alcaligenaceae which was up to 90%. However, the 3D protein visualization analysis indicated that this lipase JG3 also has the characteristic of ABC transporter protein.

Abstract: Lipase is frequently used for catalyze wide non-natural substrates in order to obtain enantio- and regioselectivie substrates. This study evaluates the stabilities of lipase by immobilization on Eupergit C. The immobilized lipase had improved stability at 60 ^oC for 60 h compared to the free lipase 1 h at 60 ^oC. Immobilization resulted in an increase in pH stability over a range of 7.0 - 9.0 and about 54 days for half-life of storage at 4 ^oC. The tolerance of lipase to organic solvents was also improved by immobilization, and the immobilized lipase showed activating activity when exposed to hydrophobic solvents.

Abstract: The enzymatic hydrolysis parameters of triacylglycerols (TAGs) in algae oil to get sn-2 glycerel monostearte including substrate amount, lipase amount and reaction time was studied, and the products of fatty acid methyl esters (FAMEs) were detected by gas chromatography (GC). The result indicated that the optimum conditions to hydrolyze TAGs in algae oil were as follows: mass ratio of substrate to lipase of 1:1, 2 mL Tris-HCl buffer, 0.2 mL CaCl₂ solution, 0.5 mL sodium cholate hydrate solution were added in each 30mg substrate, and reaction time of 1.5 min with 120 rpm at 40 °C, the highest palmitic acid (PA) content accounted for 9.1% of total oil.

Abstract: Hevea brasiliensis natural rubber (NR) latex is a very important commercial source of elastomers. It is not only a source for dry NR rubber but also the feedstock for the latex glove dipping industry. The particles of freshly tapped latex are known to be stabilized by proteins and lipids that come with the latex from the tree. These non-rubbers [, especially proteins and lipids, confer to the rubber and latex excellent properties unsurpassed by any synthetic latex [. Recent structural studies of NR revealed that the NR molecules comprise of 2 trans-isoprene units connected to a long-chain cis-isoprene units. Two terminal groups, referred to as ω and α, have been postulated to link with mono-and di-phosphate groups associated with phospholipids by H-bonding at the α-terminal, whereas the ω-terminal is a dimethylallyl group links to protein by H-bonding [. Although numerous studies have been published on the surface structure of the natural rubber particle [4-, none of these offered a direct in situ visualization of the intact particle surface. This is because of any attempt to remove this surface layer of proteins and lipids results in an immediate destabilization of the latex. The second part focused on the using of Atomic Force Microscopy (AFM) and Confocal Fluorescence microscopy to visualize and delineate the structure of the proteins and lipids layer on the latex particle surface in situ.

Abstract: Lipase from Candida rugosa (CRL) was used to catalyze the transesterification of vinyl acetate with 2-hydroxymethyl-1,4-benzodioxan in ionic liquid microemulsions (H₂O/[BmiPF₆, water in 1-butyl-3-methylimidazolium hexafluorophosphate), and the results demonstrated that CRL could preserve higher catalytic activity in H₂O/[BmiPF₆ microemulsions.

Abstract: Optimized synthesis conditions for biodiesel from microalgae oil and methanol using a modified immobilized lipase from Candida sp. as catalyst were investigated. The methanol tolerance of the immobilized lipase modified with succinic anhydride was determined. The results showed that the modified enzyme exhibited higher stability in methanol as compared with the unmodified enzyme. Then, the modified immobilized enzyme was applied to synthesize biodiesel using methanol and microalgae oil from Chlorella sp. Cells as substrates and the synthesis conditions were optimized. Tert-butanol was the most suitable organic solvent for biodiesel synthesis. The molar ratio of the reactants was found to be an important parameter affecting the yield of biodiesel. When the molar ratio of the methanol to Chlorella oil is 5:1, the yield of biodiesel catalyzed by modified lipase reaches the maximum of 92.5%. While the native immobilized Candida sp. lipase is used as catalyst, the yield of biodiesel get the maximum of 82.4% at the methanol / Chlorella oil molar ratio of 4. The reuse stabilities of the modified enzyme and unmodified enzyme were also studied in the present work. These experimental results proved that the immobilized lipase modified with succinic anhydride was suitable for the synthesis of microalgae-derived biodiesel.

Abstract: Lipase is a kind of important hydrolase. It was widely used in the fields of food, leather, detergent and pharmaceutical. The production of lipase from Arthrobacter sp. SD5 was studied in the present paper. The medium composition and culture condition were optimized in order to improve lipase production. The results showed the best optimum conditions were on the following: culture temperature (40°C); initial pH value (8.0); liquid volume (20%); carbon source (olive oil, 2.5%); nitrogen source (peptone, 1.0%); biosurfactant (Tween-80, 0.2%).

Abstract: Lower alcohol-tolerant lipases have shown potential application for synthesis of biodiesel. An Arthrobacter strain producing a lipase with lower alcohol-stability was isolated from soils. The crude lipase had stability in the presence of methanol and ethanol. 78% and 85% of the original activity was retained after incubation for 48h in methanol and ethanol at the concentration of 50%.