共查询到20条相似文献,搜索用时 15 毫秒
1.
S. Ueji R. Fujino N. Ōkubo T. Miyazawa S. Kurita M. Kitadani A. Muromatsu 《Biotechnology letters》1992,14(3):163-168
Summary In the esterification of 2-phenoxypropionic acids catalyzed byCandida
cylindracea lipase, its enantio-selectivity was inverted in non-polar solvents such as carbon tetrachloride from that in polar solvents such as acetone. A model for this inversion is suggested. 相似文献
2.
《Biocatalysis and Biotransformation》2013,31(1-4):115-121
From the comparation of esterification between oleic acid and oleyl alcohol, catalyzed by the Mucor miehei immobilized lipase in a batch stirred tank reactor, in a solvent free system and system where the solvent was supercritical carbon dioxide it is obvious that reaction rates are higher at supercritical conditions than in the solvent free system. To obtain the data on the solubility of substrates and product (oleyl oleate) in supercritical carbon dioxide, fluid phase equilibria measurements in the static equilibrium cell have been done. The results showed that the temperature change between 30 d`C and 50 d`C doesn't affect the solubility of the substances in SC CO2 very much, but with higher pressure (between 100 and 300 bar) the solubilities of oleic acid, oleyl alcohol and oleyl oleate slightly increase. From the data it is obvious that oleic acid and oleyl alcohol have better solubility in supercritical CO2 than oleyl oleate and therefore the separation of both substrates from oleyl oleate with supercritical CO2 is possible-Key words: esterification, supercritical fluids, lipase. 相似文献
3.
Summary Extracellular lipase production byCandida
rugosa growth has been studied. The main growth parameters, and the lipase activity in the culture broth were determined in order to identify the maximum of enzyme activity.The effect of lipidic material and size and growth phase of the inoculum on enzymatic production have been studied. Maximum extracellular lipase activity was associated with an increase in enzyme production when the number of viable cells started to decrease. 相似文献
4.
Yoh Kodera Katsunobu Takahashi Hiroyuki Nishimura Ayako Matsushima Yuji Saito Yuji Inada 《Biotechnology letters》1986,8(12):881-884
Summary Lipase fromCandida
cylindracea was coupled with polyethylene glycol(PEG). In contrast to the previously used lipase fromPseudomonas
fluorescens, the modified lipase catalyzed the ester synthesis in benzene at 25°C from short-chain alcohols and - or -substituted carboxylic acid. Using the modified lipase, following esters were synthesized; pentyl -methylpentanate, methyl benzoate, and methyl retinoate. 相似文献
5.
Preparation of monomeric acrylic ester intermediates using lipase catalysed transesterifications in organic solvents 总被引:2,自引:0,他引:2
Summary Acrylate monoesters were synthesized on a preparative scale by the regioselective enzymatic transesterification of a range of diols dissolved in ethyl acrylate using a commercial lipase fromChromobacterium
viscosum. 相似文献
6.
Summary n-Alkyl sec-alkyl carbonates were enantioselectively hydrolyzed by porcine pancreatic lipase to give optically active (R)-sec-alkanols. (R)-1-Phenylethanol with an optical purity of >99%ee was obtained by the resolving method. 相似文献
7.
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
8.
Summary Some nutritional factors that affect lipase yields byRhizopus
delemar were studied. Dextrin proved to be the best carbon source when used at 1% level. Yeast extract was the best nitrogen source for lipase production. The presence of a lipidic source in the growth medium, at a level not higher than 2% resulted in higher enzyme production. Tween 80 exerted a positive effect on enzyme production, used in a range that goes from 0.02% to 2.00%. 相似文献
9.
Yutaka Tamaura Katsunobu Takahashi Yoh Kodera Yuji Saito Yuji Inada 《Biotechnology letters》1986,8(12):877-880
Summary A ferromagnetic modifier was prepared by reacting ferrous(Fe2+)- and ferric(Fe3+)-ions with polyethylene glycol having two carboxyl groups (MW:2000) at pH 8.0–8.5. Lipase fromPseudomonas
fragi 22–39B was coupled with the modifier using water-soluble carbodiimide. The modified lipase, which was dispersed into buffered solutions in the size range of 30–70 nm, exerted the hydrolytic activity of 8.0 U/mg. In a magnetic field of 250 Oe, the ferromagnetic-modified lipase was readily recovered from the colloidal solution. 相似文献
10.
Production of flavor esters by immobilized lipase 总被引:5,自引:0,他引:5
Summary
Candida
cylindracea lipase adsorbed to silica gel produced a variety of flavor esters when hydrated and shaken in n-heptane containing substrates. Scale-up production of ethyl butyrate was examined in a packed column with recycling of n-hexane containing substrates. Increased substrate concentrations were stimulatory up to a point after which inhibition and enzyme destabilization in repeated runs occurred. 相似文献
11.
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
12.
Mertxe de Renobales I. Agud J. M. Lascaray J. C. Múgica L. C. Landeta R. Solozábal 《Biotechnology letters》1992,14(8):683-688
Summary We have studied the hydrolysis of high melting animal fats by the lipase fromCandida
rugosa at temperatures between 20°C and 37°C without the addition of surfactants or organic solvents. To establish the practical applications of this process we investigated the optimal conditions of the reaction at high substrate concentrations (50% fat w/v) to achieve 95% hydrolysis (or better) in 24 hours. Experiments were conducted in solid emulsions without constant stirring (500 ml total reaction volume). Under all conditions tested, edible pork lard was a better substrate than inedible beef tallow yielding up to 96% hydrolysis with as low as 0.3 g lipase/Kg fat or 98% hydrolysis with 0.5 g lipase/Kg fat. The optimum temperature for the hydrolysis of edible pork lard was around 30°C. Inedible beef tallow and pork lard did not exhibit a clear optimum temperature. Inedible lard gave results intermediate between those of edible lard and inedible beef tallow. 相似文献
13.
Summary
Candida
rugosa lipase immobilized by adsorption on the swollen Sephadex LH-20 and Sephadex LH-60 could effectively hydrolyze olive oil at high concentration in a reverse phase system. Initial water content was found to be the most important factor that determines both the hydrolysis rate and the degree of hydrolysis; approximately 54% of water in the gels was readily utilized. 相似文献
14.
T. Nishio K. Takahashi T. Yoshimoto Y. Kodera Y. Saito Y. Inada 《Biotechnology letters》1987,9(3):187-190
Summary Lipase fromPseudomonas
fragi modified with polyethylene glycol was soluble and active in organic solvents such as benzene and chlorinated hydrocarbons. Using the modified lipase, terpene alcohol esters were synthesized with various combinations of terpene alcohols (citronellol, geraniol, farnesol and phytol) and carboxylic acids (acetic-, propionic-, n-butyric-, and valeric acids) in benzene at 25°C. The yield was generally very high. 相似文献
15.
Summary Three distinct forms of lipolytic enzyme were identified in a commercialCandida lipase preparation. Two of these lipases (lipases A & C) were isolated and characterized. Lipase A had a higher optimal reaction pH and a better thermal stability than those of lipase C. Lipase A and C displayed different acyl chain length specificity on the lipolysis of p-nitrophenol esters. 相似文献
16.
Sunil Kumar Narwal Nitin Kumar Saun Priyanka Dogra Reena Gupta 《Russian Journal of Bioorganic Chemistry》2016,42(1):69-73
Isoamyl acetate, a pear or banana flavor, is widely used in food, beverage, cosmetic, and pharmaceutical industries. In the present work, lipase from Bacillus aerius was immobilized on silica gel matrix in the presence of a cross-linking agent, glutaraldehyde, and its efficiency in synthesizing isoamyl acetate using esterification reaction was studied. The esterification of acetic acid and isoamyl alcohol by silica-bound lipase was studied as a function of time and temperatures. The incubation time of 10 h, temperature of 55°C, substrate molar ratio 1: 1, and the amount of lipase as 1% were found to be optimal for the esterification reaction. The bound lipase catalyzed the esterification of acetic acid by isoamyl alcohol with the yield of about 68% under the optimized reaction conditions. The product was identified as isoamyl acetate using gas-liquid chromatography, nuclear magnetic resonance, and Fourier transform IR spectroscopy analysis by the presence of an ester group at the wavenumber of 1720.5 cm–1. 相似文献
17.
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
18.
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
19.
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
20.
Summary In a two-phase system of D-sorbitol in water and decanoic acid the esterification is catalyzed by lipase fromCandida rugosa. The initial esterification rate is 3.0 mmole/g.h and is strongly dependent on the water content of the reaction mixture. In a two-phase membrane reactor the initial esterification rate is 6.8 mmole/g.h. After 570 hours this reaction rate is reduced by 15%, which indicates a fairly good stability of lipase in this membrane system. 相似文献