共查询到20条相似文献,搜索用时 31 毫秒
1.
Use of lipases in the resolution of racemic ibuprofen 总被引:5,自引:0,他引:5
Annikka Mustranta 《Applied microbiology and biotechnology》1992,38(1):61-66
Summary Resolution of (R,S)-ibuprofen enantiomers by esterification in different organic solvents was studied using Candida cylindracea lipase. This enzyme preparation had high enantiospecificity for S(+)-ibuprofen in the esterification reaction of a racemic ibuprofen with primary alcohols. The esterification yields of secondary alcohols were much lower than those of primary alcohols. Esterification with tertiary alcohols was not observed. The synthesis of esters was profoundly affected by the amount of water in the reaction mixture. C. cylindracea lipase was active only in very hydrophobic solvents. The esterification activity of the lipase was reduced significantly by addition of water. The R- and S-enantiomers of ibuprofen were determined without derivatization by HPLC using a chiral column. 相似文献
2.
Synthesis and Biological Evaluation of New Natural Phenolic (2E,4E,6E)‐Octa‐2,4,6‐trienoic Esters
下载免费PDF全文
![点击此处可从《化学与生物多样性》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Raffaella Gandolfi Alessandro Contini Daniela Pinto Barbara Marzani Stefano Pandini Donatella Nava Elena Pini 《化学与生物多样性》2017,14(12)
In the present study the esterification of the OH groups of resveratrol, caffeic acid, ferulic acid, and β‐sitosterol with an antioxidant polyconjugated fatty acid, (2E,4E,6E)‐octa‐2,4,6‐trienoic acid, was achieved. As the selective esterification of OH groups of natural compounds can affect their biological activity, a selective esterification of resveratrol and caffeic acid was performed by an enzymatic approach. The new resulting compounds were characterized spectroscopically (FT‐IR, NMR mono, and bidimensional techniques); when necessary the experimental data were integrated by quantum chemical calculations. The antioxidant, anti‐inflammatory and proliferative activity was evaluated. The good results encourage the use of these molecules as antioxidant and/or anti‐inflammatory agents in dermocosmetic application. 相似文献
3.
Enzymatic kinetic resolution of racemic 1-phenylethanol catalysed by immobilized Candida antarctica lipase B was investigated in a neat system at the temperature range of 30–70?°C. Synthetic triglycerides, namely glycerol triacetate and glycerol tributyrate, were applied as the esterification agents. Both esterification agents were efficient regarding to the enantioselectivity (>1000). Initial rate of reaction and the kinetic constants were influenced by the applied esterification agent significantly. A detailed modelling approach is presented and verified in the temperature range on 30–60?°C for the tributyrin system. 相似文献
4.
Ramesh N. Patel Jeffrey M. Howell Amit Banerjee Kenneth F. Fortney Laszlo J. Szarka 《Applied microbiology and biotechnology》1991,36(1):29-34
Summary A key intermediate, S-(–)-3-benzoylthio-2-methylpropanoic acid (1) was made in high optical purity by the lipase-catalyzed stereoselective esterification of racemic 1 with methanol in an organic solvent system. Among various lipases evaluated, Amano P-30 lipase from Pseudomonas sp. efficiently catalyzed the esterification of 1 to yield R-(+) methyl ester and unreacted S-(–) 1. A reaction yield of 40 mol% and an optical purity of 97.2% were obtained for compound 1 at a substrate concentration of 0.1 m (22 mg/ml). Lipase P-30 was immobilized on Accurel polypropylene (PP) and the immobilized enzyme was reused (23 cycles) in the esterification reaction without loss of enzyme acitivity, productivity or optical purity. Among various solvents evaluated, toluene was found to be the most suitable organic solvent and methanol was the best alcohol for the esterification of racemic 1 by immobilized lipase. Substrate concentrations as high as 1.0 m were used in the esterification reaction. When the temperature was increased from 28° C to 60° C, the reaction time required for the esterification of 0.1 m substrate decreased from 16 h to 2 h. On increasing the methanol to substrate molar ratio from 1:1 to 4:1, the rate of esterification decreased. A lipase fermentation using Pseudomonas sp. ATCC 21 808 was developed. In the batch-fermentation process, 56 units/ml of extracellular lipase activity was obtained. A fed-batch process using soybean oil gave a significant increase in the lipase activity (126 units/ml). Crude lipase recovered from the filtrate by ethanol precipitation and immobilized on Accurel PP was also effective: S-(–) compound 1 was obtained in 35 mol% yield and 95% optical purity.
Offsprint requests to: R. N. Patel 相似文献
5.
Marceli Fernandes Silva Denise M. G. Freire Aline Machado de Castro Marco Di Luccio Marcio A. Mazutti J. Vladimir Oliveira Helen Treichel D��bora Oliveira 《Bioprocess and biosystems engineering》2011,34(2):145-152
The main objective of this work was to optimize lipase production, in terms of hydrolytic and esterification activities, by
Penicillium brevicompactum and Penicillium verrucosum in solid state fermentation using agroindustrial residues as raw material. Maxima hydrolytic activities of 48.6 and 87.7 U/g
were achieved when P. brevicompactum was cultured in babassu cake and castor meal, respectively. Higher esterification activities (around 244 U/g) were achieved
when P. brevicompactum was used as microorganism and babassu cake as raw material. Different experimental conditions led to these promising values,
clearly showing that no correlation can be attributed between hydrolytic and esterification activities. In spite of the several
applications of lipases which are capable of catalyze synthesis reactions, only few works in this subject are presented in
the literature, especially when low cost raw materials are used. 相似文献
6.
Commercial lipase preparations and mycelium bound lipase from Aspergillus niger NCIM 1207 were used for esterification of acetic acid with isoamyl alcohol to obtain isoamyl acetate. The esterification
reaction was carried out at 30°C in n-hexane with shaking at 120 rpm. Initial reaction rates, conversion efficiency and isoamyl acetate concentration obtained
using Novozyme 435 were the highest. Mycelium bound lipase of A. niger NCIM 1207 produced maximal isoamyl acetate formation at an alcohol/acid ratio of 1.6. Acetic acid at higher concentrations
than required for the critical alcohol/acid ratio lower than 1.3 and higher than 1.6 resulted in decreased yields of isoamyl
acetate probably owing to lowering of micro-aqueous environmental pH around the enzyme leading to inhibition of enzyme activity.
Mycelium bound A. niger lipase produced 80 g/l of isoamyl acetate within 96 h even though extremely less amount of enzyme activity was used for esterification.
The presence of sodium sulphate during esterification reaction at higher substrate concentration resulted in increased conversion
efficiency when we used mycelium bound enzyme preparations of A. niger NCIM 1207. This could be due to removal of excess water released during esterification reaction by sodium sulphate. High
ester concentration (286.5 g/l) and conversion (73.5%) were obtained within 24 h using Novozyme 435 under these conditions. 相似文献
7.
Erland Holmberg Mats Holmquist Erik Hedenström Per Berglund Torbjörn Norin Hans-Erik Högberg Karl Hult 《Applied microbiology and biotechnology》1991,35(5):572-578
Summary We have demonstrated resolution of 2-methylalkanoic acids using lipase from Candida cylindracea as a catalyst. The resolution of 2-methyldecanoic acid was more successful than that of 2-methylbutyric acid both by esterification and hydrolysis. This indicates that the resolution of the acid is dependent on the chain length of the acid moiety. The chain length of the alcohol moiety of the ester affected the resolution of the long-chain acid only. Using esterification, (R)-2-methyldecanoic acid was produced in an enantiomeric excess (e.e.) of 95% (E = 40). If the enantiomeric ratio is low (E = 3.6), as in the resolution of 2-methylbutyric acid, esterification combined with a high equilibrium conversion could be used to yield the remaining acid in a high e.e. In the hydrolytic reactions, the e.e and the equilibrium conversion were dependent on the pH and the presence of CaCl2. When octyl 2-methyldecanoate was hydrolysed at pH 8.0 in the presence of CaCl2, the (S)-acid was formed with an e.e. of 80% (E = 9), but when the hydrolysis was carried out at pH 7.5 without CaCl2, a very low e.e. and a low equilibrium conversion were observed. The latter conditions allowed the esterification of 2-methyldecanoic acid with 1-octanol even in aqueous medium.
Offprint requests to: K. Hult 相似文献
8.
Thermomyces lanuginosus lipase (Lipozyme TLIM)-catalyzed esterification of l-ascorbic acid was studied. It was suggested that Lipozyme TLIM was a suitable biocatalyst for enzymatic esterification of
l-ascorbic acid. Three solvents were investigated for the reaction, and acetone was found to be a suitable reaction medium.
Furthermore, it was found that water activity could notably affect the conversion. Moreover, pH memory of Lipozyme TLIM lipase
for catalyzing l-ascorbic acid esterification in acetone was observed and the effect of pH on the reaction was estimated. In addition, the
influences of other parameters such as substrate mole ratio, enzyme loading, and reaction temperature and reusability of lipase
on esterification of l-ascorbic acid were also analyzed systematically and quantitatively. Kinetic characterization of Lipozyme TLIM showed that
K
m,a and V
max were 80.085 mM and 0.747 mM min−1, respectively. As a result, Lipozyme TLIM-catalyzed esterification of l-ascorbic acid gave a maximum conversion of 99%. 相似文献
9.
Dong-Hao Zhang Ya-Qiong Li Chao Li Yv-Qin Lv Yang Li 《Biotechnology and Bioprocess Engineering》2012,17(1):60-66
L-ascorbyl acetate was synthesized through lipase-catalyzed esterification using Lipozyme TLIM and Novozym 435. Four solvents,
including methanol, ethanol, acetonitrile, and acetone were investigated for the reaction, and acetone and acetonitrile were
found to be suitable reaction media. The influences of several parameters such as water activity (a
w), substrate molar ratio, enzyme loading, and reaction temperature on esterification of L-ascorbic acid were systematically
and quantitatively analyzed. Through optimizing the reaction, lipase-catalyzed esterification of L-ascorbic acid gave a maximum
conversion of 99%. The results from using Lipozyme TLIM and Novozym 435 as biocatalysts both showed that a
w was an important factor for the conversion of L-ascorbic acid. The effect of pH value on lipase-catalyzed L-ascorbic acid
esterification in acetone was also investigated. Furthermore, results from a kinetic characterization of Lipozyme TLIM were
compared with those for Novozym 435, and suggested that the maximum reaction rate for Lipozyme TLIM was greater than that
for Novozym 435, while the enzyme affinity for substrate was greater for Novozym 436. 相似文献
10.
Spectral changes and esterification (presumably with phytol) of newly formed chlorophyllide a in dark-grown leaves of wildtype bean (Phaseolus vulgaris) and barley (Hordeum vulgare) and a number of chloroplast mutants in barley, were studied by spectrofluorimetry on leaves and on solvent extracts. The shift of the fluorescence emission maximum from 692–694 to 678 nm (excitation shift: 682–684 to 672 nm) and esterification of chlorophyllide a have a similar time course, and both processes are temperature dependent in a similar manner. After completion of the spectral shift and esterification, the fluorescence efficiency of chlorophyll a increases with a subsequent reaccumulation of protochlorophyllide. In leaves of mutants where the shift of fluorescence from 692 to 678 nm is lacking, esterification and the subsequent processes are also blocked. In leaves of mutants with a rapid shift of the fluorescence from 692 to 678 nm, or with direct photoconversion to chlorophyllide a with the fluorescence at 678 nm, esterification is also rapid. The results are interpreted as a sequence of molecular events involving a conformational relaxation of the chlorophyllide holochrome and a translocation of chlorophyll a to reaction centers of the photosystems. 相似文献
11.
《Biocatalysis and Biotransformation》2013,31(5):355-371
Enrichment of n-3 polyunsaturated fatty acids from sardine cannery effluents upon enzymatic esterification by Lipozyme® was optimized in batch and in continuous processes. In these processes, the yield of docosahexaenoic acid (DHA) (Y1) and the yield of eicosapentaenoic acid (EPA) (Y2), in the residual acid fraction were maximized. In batch, a two-factor Doehlert design was used to study the effects of temperature and ratio of fatty acid to alcohol. Second order polynomial regression models for Y1 and Y2 were postulated to generate response surfaces. After esterification the fraction of fatty acid was enriched to 70% with DHA or to 44% with EPA. In a continuous process, a three-factor central composite design was employed to study the effects of temperature, ratio of fatty acid to alcohol and flow rate. Second order polynomial regression models for Y1 and Y2 were used to generate response surfaces. After esterification, a quantity of DHA close to 30% and 17% of EPA. 相似文献
12.
Comparison of direct esterification and transesterification of fructose by Candida antartica lipase 总被引:2,自引:0,他引:2
Fructose oleates synthesis was performed in a batch reactor by trans- or direct esterification. An immobilized lipase from Candida antartica was used. When a solvent was used, 65% and 46% of conversion of fructose were obtained by transesterification and direct esterification, respectively. These two reactions were also compared in a solvent-free melt. Both in molten media and with cosolvent, two isomeric forms of fructose oleates were produced. 相似文献
13.
The enantioselective esterification of ibuprofen catalyzed by Novozym40086 was successfully conducted in organic solvent. Removing‐water reagent was added into the reaction mixture to remove water produced in the esterification. The effects of temperature, n‐hexanol concentration, ibuprofen concentration, and loading of enzymes were investigated. Under the condition of equilibrium, the thermodynamic equilibrium constant (K) of 7.697 and enantioselectivity (E) of 8.512 were obtained. The esterification reaction achieved its equilibrium in approximately 30 hours with conversion of 56% and eeS of 93.78%. The predicted values of X and eeS were 67.90% and 95.60%, respectively. The experimental value is approximately equal to the theoretical value, which indicates the feasibility of ideal models. 相似文献
14.
The esterification reaction between stearic acid and lactic acid using Rhizomucor miehei lipase and porcine pancreas lipase was optimized for maximum esterification using response surface methodology. The formation
of the ester was found to depend on three parameters namely enzyme/substrate ratio, lactic acid (stearic acid) concentration
and incubation period. The maximum esterification predicted by theoretical equations for both lipases matched well with the
observed experimental values. In the case of R. miehei lipase, stearoyl lactic acid ester formation was found to increase with incubation period and lactic acid (stearic acid)
concentrations with maximum esterification of 26.9% at an enzyme/substrate (E/S) ratio of 125 g mol−1. In the case of porcine pancreas lipase, esterification showed a steady increase with increase in incubation period and lactic
acid (stearic acid) concentration independent of the E/S ratios employed. In the case of PPL, a maximum esterification of
18.9% was observed at an E/S ratio of 25 g mol−1 at a lactic acid (stearic acid) concentration of 0.09 M after an incubation period of 72 h.
Received: 12 February 1999 / Received revision: 31 May 1999 / Accepted: 4 June 1999 相似文献
15.
To increase the activity of Rhizomucor miehei lipase (RML) in organic solvent, multiple sequence alignments and rational site-directed mutagenesis were used to create
RML variants. The obtained proteins were surface-displayed on Pichia pastoris by fusion to Flo1p as an anchor protein. The synthetic activity of four variants showed from 1.1- to 5-fold the activity
of native lipase in an esterification reaction in heptane with alcohol and caproic acid as substrates. The increase in esterification
activity may be attributed to the four mutations changing the flexibility of RML or facilitating the reaction. In conclusion,
this method demonstrated that multiple sequence alignments and rational site-directed mutagenesis combined with yeast display
technology is a faster and more effective means of obtaining high-efficiency esterification lipase variants compared with
previous similar methods. 相似文献
16.
Isooctane was the best reaction medium for the enantioselective esterification of (R,S)-2-methylalkanoic acid with n-butanol using Carica papaya lipase as catalyst. Increasing linear alkyl-chain length of racemic 2-methylalkanoic acids from ethyl to hexyl increased
the enantioselectivity (E) from 2.1 to 98.2 for the esterification of racemic 2-methylalkanoic acids with n-butanol at 35°C. Decreasing reaction temperature from 40 to 20°C increased the enantioselectivity (E) from 14 to 33 for the esterification of racemic 2-methylhexanoic acids with n-butanol. We obtained a maximum enantioselectivity, of E = 24.3, for the enantioselective esterification of racemic 2-methylhexanoic acids with n-butanol in isooctane at water activity 0.33, and at 35°C. 相似文献
17.
Optimization of enantioselective resolution of racemic ibuprofen by native lipase from Aspergillus niger 总被引:1,自引:0,他引:1
de O Carvalho P Contesini FJ Bizaco R Calafatti SA Macedo GA 《Journal of industrial microbiology & biotechnology》2006,33(8):713-718
Resolution of (R,S)-ibuprofen (2-(4-isobutylphenyl)propionic acid) enantiomers by esterification reaction with 1-propanol in different organic solvents was studied using native Aspergillus niger lipase. The main variables controlling the process (enzyme concentration and 1-propanol:ibuprofen molar ratio) have been optimized using response surface methodology based on a five-level, two-variable central composite rotatable design, in which the selected objective function was enantioselectivity. This enzyme preparation showed preferentially catalyzes the esterification of R(−)-ibuprofen, and under optimum conditions (7% w/v of enzyme and molar ratio of 2.41:1) the enantiomeric excess of active S(+)-ibuprofen and total conversion values were 79.1 and 48.0%, respectively, and the E-value was 32, after 168 h of reaction in isooctane. 相似文献
18.
Acid anhydrides were used as highly reactive and non-water-producing acyl donors for hydrolase-catalyzed enantioselective esterification. Efficient kinetic resolution of dl-menthol has been achieved via lipase-catalyzed enantioselective esterification in cyclohexane when propionic anhydride as an acyl donor was continuously fed into a reactor containing dl-menthol and Candida cylindracea lipase OF 360, while a high concentration of the acid anhydride in a batch reaction system with a dehydrated organic solvent did not facilitate the reaction, because water necessary for the enzyme function was consumed by the competing hydrolysis of the anhydride catalyzed by the same enzyme. The efficiency of this fed-batch reaction system using acid anhydride was higher and the enzyme stability in repeated use was much better than those of conventional batch and fed-batch reaction systems using propionic acid as an acyl donor. The optical purity (more than 98% e.e.) of the l-menthyl ester produced in the fed-batch system using the anhydride was comparable to that in the system using the corresponding acid. *** DIRECT SUPPORT *** AG903062 00002 相似文献
19.
B. Wen A. Ström A. Tasker G. West G. A. Tucker 《Plant biology (Stuttgart, Germany)》2013,15(6):1025-1032
Post‐harvest storage is largely limited by fruit softening, a result of cell wall degradation. Pectin methylesterase (PE) (EC 3.1.1.11) is a major hydrolase responsible for pectin de‐esterification in the cell wall, a response to fruit ripening. Two major PE isoforms, PE1 and PE2, have been isolated from tomato (Solanum lycopersicon) pericarp tissue and both have previously been down‐regulated using antisense suppression. In this paper, PE1 and PE2 double antisense tomato plants were successfully generated through crossing the two single antisense lines. In the double antisense fruit, approximately 10% of normal PE activity remained and ripening associated pectin de‐esterification was almost completely blocked. However, double antisense fruit softened normally during ripening. In tomato fruit, the PE1 isoform was found to contribute little to total PE activity and have little effect on the degree of esterification of pectin. In contrast, the other dominant fruit isoform, PE2, has a major impact on de‐esterification of total pectin. PE2 appears to act on non‐CDTA‐soluble pectin during ripening and on CDTA‐soluble pectin before the start of ripening in a potentially block‐wise fashion. 相似文献
20.
Andreas Buthe Tobias Recker Matthias Heinemann Winfried Hartmeier Jochen Büchs 《Biocatalysis and Biotransformation》2013,31(5):307-314
Though lipases are frequently applied in ester synthesis, fundamental information on optimal pH or substrate concentration, can almost only be found for the reverse reaction – hydrolysis. This study demonstrates that the pH-optima of lipase-catalysed esterifications differ significantly from the optima of the hydrolysis reaction. In the esterification of n-butanol and propionic acid with lipases of Candida rugosa (CRL) and Thermomyces lanuginosa (TLL) pH-optima of 3.5 and 4.25, respectively, were found. This is about 3–4 units (CRL) and 7 units (TLL) in pH lower than optimum for hydrolysis. Enzyme activity increased with increasing concentrations of protonated acid indicating that the protonated acid rather than the deprotonated form is substrate for esterification. The rate of esterification can be drastically increased by ensuring acid concentrations up to 1000 mmol L?1 for CRL and 600 mmol L?1 for TLL in the reaction system. 相似文献