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61.
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Fabricio M. Gomes Grazielle S. Silva Daltro G. Pinatti Rosa A. Conte Heizir F. de Castro 《Applied biochemistry and biotechnology》2005,121(1-3):255-268
The objective of this work was to select an efficient methodology for preparing active samples of Candida rugosa lipase immobilized in wood cellulignin, to be applied in hydrolysis and ester reactions. For this purpose, lipase was immobilized
in the matrix by physical adsorption (pure cellulignin) and covalent binding (activated cellulignin with glutaraldeyde or
carbonyldiimidazole [CDI]) in the presence or absence of polyethylene glycol (PEG) (Molecular mass of 1500 Daltons) as stabilizing
agent. The activating agent and the presence of PEG-1500 in the immobilization procedure showed a strong influence on enzyme
retention in the support. The values for enzyme retention ranged from 20 to 68%, and the highest yield was obtained when the
enzyme was immobilized in cellulignin activated with CDI in the presence of PEG-1500. This immobilized derivative presented
high hydrolytic (193.27 μM/[mg·min]) and synthetic (522.92 μM/[g·min]) activities when compared with those obtained by other techniques. The superiority of this immobilized system was
confirmed by additional analyses, such as infrared spectroscopy and elemental analysis, which demonstrated an appropriate
enzyme fixation and the highest level of protein incorporation in the support. Further information on the immobilized derivative
was obtained by assessing the recycle potential in both aqueous and nonaqueous media. 相似文献
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Silica nanoparticles were first used as the carrier for the porcine pancreas lipase (PPL) immobilization. The result of transmission electron microscopy (TEM) showed that the immobilized lipase was still in nanosize after enzyme immobilization. The ring-opening polymerization of 2,2-dimethyltrimethylene carbonate (DTC) catalyzed by this immobilized PPL (IMPPL) was explored. 1H NMR spectra suggested no evidence of decarboxylation during propagation. Influences of IMPPL concentration and reaction temperature on the molecular weight and yield of poly(DTC) were studied. The recovery and reuse of IMPPL for the ring-opening polymerization of DTC was also investigated. The recycling IMPPL showed even higher catalytic activity and a higher molecular weight of polycarbonate could be achieved. 相似文献
66.
A.?Karout P.?Buisson A.?Perrard A.?C.?PierreEmail author 《Journal of Sol-Gel Science and Technology》2005,36(2):163-171
The synthesis of silica aerogels reinforced with either carbon or silica fibre felts and which encapsulate the lipase PS of Amano (LPS AB025407) obtained from Burkholderia cepacia is described. The materials were further shaped by moulding them in Teflon® tubes. The silica aerogels were synthesized with various ratios of hydrophobic groups and dried according to the supercritical CO2 method. Both types of reinforcements improve the catalytic activity of the material per mass of lipase. The fibre felts reinforcements also enable the encapsulation of higher concentrations of lipase. The materials were shaped into small moulded monoliths, which were readily washed and recycled without significant mechanical deterioration or loss of catalytic activity. In addition, hydrophobic carbon felts reinforce more efficiently silica aerogels that incorporate a high ratio of hydrophobic groups, while silica felts strengthen those aerogels that carry a low proportion of hydrophobic groups. 相似文献
67.
Abstract The effect of high temperature and high hydrostatic pressure on the residual hydrolytic activity of a commercial Rhizomucor miehei lipase has been studied. Inactivation at high temperature and/or high pressure was carried out. Under non-denaturing pressure conditions, results showed that pressurisation protects enzymes against thermal deactivation. This is in accordance with previous results obtained with enzymes from mesophilic sources, such as invertase and galactosidases. 相似文献
68.
In this paper, a biocatalytic route is described wherein PPL, lipase from porcine pancreas, in conjunction with water on reaction with different thiophenols and styrene oxides undergo thiolysis with C-S bond formation without the use of any metal catalysts, oxidants, bases, additives or organic solvents towards formation of β-hydroxysulfides in good to excellent yields with high regioselectivity at room temperature. Furthermore, PPL also facilitates thiophenols to undergo hydrothiolation with styrenes or phenylacetylenes in sole water and thus forming linear thioethers or vinylsulfides respectively via C–S bond formation. In addition to the straightforward and atom-efficient protocol, a gram-scale synthesis of β-hydroxysulfide and recyclability for three consecutive cycles without decrease in efficiency of PPL make our biocatalytic protocol for constructing C–S bond highly valuable from both environmental and economic viewpoints than traditional chemical practices. 相似文献
69.
《中国化学会会志》2018,65(6):696-705
Magnetic porous polymeric microspheres containing epoxy groups were prepared by suspension polymerization (denoted as magnetic Fe3O4@GEM microspheres). Fe3O4@GEM with a specific surface area of 30.41 m2/g, average pore diameter of 17.13 nm, and pore volume of 0.13 cm3/g exhibited superparamagnetic behavior with the saturation magnetization of 7.1 emu/g. The content of epoxy groups on Fe3O4@GEM was 0.22 mmol/g. Pseudomonas sp. lipase (PSL) was covalently immobilized onto the Fe3O4@GEM microspheres through the reaction between the amino groups of the enzyme and the epoxy groups on the microspheres. PSL/Fe3O4@GEM exhibited enhanced enantioselectivity for the resolution of allylic alcohol to the corresponding optically active (S)‐allylic alcohol and (R)‐allylic alcohol acetate compared to free PSL. The enantiomeric excess of (S)‐l‐pheny‐2‐propen‐1‐ol for the former (98.1%) was 81.7 times that of the latter (1.2%) when the immobilized PSL was used for transesterification resolution of (R,S)‐l‐pheny‐2‐propen‐1‐ol. Furthermore, the ees and eep values were still retained at 95.2% and 95.4% after PSL/Fe3O4@GEM was recycled 10 times, indicating that PSL/Fe3O4@GEM had very good reusability. In addition, the transesterification resolution of (R,S)‐1‐(4‐methylphenyl)‐2‐propen‐1‐ol and (R,S)‐1‐(4‐bromophenyl)‐2‐propen‐1‐ol was catalyzed by PSL/Fe3O4@GEM, affording ideal ees and eep values of 99.3%, 97.4% and 99.6%, 98.2%, respectively. Therefore, PSL/Fe3O4@GEM demonstrated its potential as a highly efficient enzymatic reactor and Fe3O4@GEM would be very promising carriers for immobilizing enzymes in industrial application. 相似文献
70.
Lipase‐Catalyzed Dynamic Kinetic Resolution of C1‐ and C2‐Symmetric Racemic Axially Chiral 2,2′‐Dihydroxy‐1,1′‐biaryls 下载免费PDF全文
Dr. Gamal A. I. Moustafa Yasuhiro Oki Prof. Dr. Shuji Akai 《Angewandte Chemie (International ed. in English)》2018,57(32):10278-10282
We have discovered that the racemization of configurationally stable, axially chiral 2,2′‐dihydroxy‐1,1′‐biaryls proceeds with a catalytic amount of a cyclopentadienylruthenium(II) complex at 35–50 °C. Combining this racemization procedure with lipase‐catalyzed kinetic resolution led to the first lipase/metal‐integrated dynamic kinetic resolution of racemic axially chiral biaryl compounds. The method was applied to the synthesis of various enantio‐enriched C1‐ and C2‐symmetric biaryl diols in yields of up to 98 % and enantiomeric excesses of up to 98 %, which paves the way for new developments in the field of asymmetric synthesis. 相似文献