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1.
Hao-Ping Chen Kwo-Feng Hsiao Shih-Hsiung Wu Kung-Tsung Wang 《Biotechnology letters》1995,17(3):305-308
Lipase fromAspergillus niger was partially purified by a single step of ion-exchange chromatography and two major fractions I and II could be obtained. Two substrates, peracetylated 1-methyl and 1-thioethyl -D-glucopyranosides, were deacetylated by fraction II to give 3-OH derivatives as sole products with very high yield, respectively. 相似文献
2.
J W Dorner 《Applied microbiology》1983,46(6):1435-1437
Production of the mycotoxin cyclopiazonic acid by Aspergillus tamarii Kita is reported for the first time. Examination of 23 isolates of the fungus showed that 22 produced the toxin under the culture conditions utilized. 相似文献
3.
Donna M. Gibson 《Biotechnology letters》1987,9(5):305-310
Summary Cultures grown on Hylon corn starch media produced the highest levels of phytase. Phospholipid extraction of Hylon starch did not change its effectiveness as a substrate. Cultures grown on phosphorylated dextrins from Hylon corn starch produced equivalent amounts of phytase. 相似文献
4.
The possibility of using Bacillus flexus XJU-1 lipase in detergent preparations was studied. The enzyme was monomeric protein as confirmed by liquid chromatography-mass spectrometry and its molecular weight was 15.95 kDa. The lipase showed optimum activity at pH 10.0 and was 100% stable for 24 h at pH 10.0 and 11.0. It exhibited maximum activity at 70°C and retained more than 70% of the initial activity at 60, 70 and 80°C for 24 h. The activity was stimulated by Ca2+, Ba2+, Mg2+ and Co2+, whereas 50% of the initial activity was lost with Fe3+ and Hg2+. The activity was inhibited by 10 mM N-bromosuccinimide and tosyl-L-lysylchloromethylketone, while N-ethylmaleimide, phenylmethylsulphonylfluoride and urea did not show any effect. The enzyme significantly hydrolysed olive, cottonseed, sunflower, groundnut, and gingelly oils. With p-nitrophenyl palmitate, Vmax and Km were 62.5 U/mL and 2.25 mM, respectively. The lipase maintained its stability in Tween-80, Triton-100 and H2O2 at 1%, but an activation of 10% and a reduction of 15% in relative activity were observed with NaClO and sodium dodecyl sulphate, respectively. The enzyme retained maximum storage stability for 20 days at ?20, 4 and 30°C. In the presence of 0.7% (w/v) Ariel, Henko, Super wheel, Tide plus and Rin, a retention of more than 84.90% initial activity was recorded after 24 h at 60°C. The supplementation of the lipase to the detergents improved the olive oil stain removal. These properties suggested the present enzyme as a potential additive for detergent preparations. 相似文献
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6.
The action of bile salts and other detergents on pancreatic lipase and the interaction with colipase 总被引:2,自引:0,他引:2
B Borgstr?m 《Biochimica et biophysica acta》1977,488(3):381-391
7.
Lipases catalyze the hydrolysis of triglycerides and are activated at the water-lipid interface. Thus, their interaction with amphiphiles such as detergents is relevant for an understanding of their enzymatic mechanism. In this study, we have characterized the effect of nonionic, anionic, cationic, and zwitterionic detergents on the enzymatic activity and thermal stability of Thermomyces lanuginosus lipase (TlL). For all detergents, low concentrations enhance the activity of TlL toward p-nitrophenyl butyrate by more than an order of magnitude; at higher detergent concentrations, the activity declines, leveling off close to the value measured in the absence of detergent. Surprisingly, these phenomena mainly involve monomeric detergent, as activation and inhibition occur well below the cmc for the nonionic and zwitterionic detergents. For anionic and cationic detergents, activation straddles the monomer-micelle transition. The data can be fitted to a three state interaction model, comprising free TlL in the absence of detergent, an activated complex with TlL at low detergent concentrations, and an enzyme-inhibiting complex at higher concentrations. For detergents with the same headgroup, there is an excellent correspondence between carbon chain length and ability to activate and inhibit TlL. However, the headgroup and number of chains also modulate these effects, dividing the detergents overall into three broad groups with rising activation and inhibition ability, namely, anionic and cationic detergents, nonionic and single-chain zwitterionic detergents, and double-chain zwitterionic detergents. As expected, only anionic and cationic detergents lead to a significant decrease in lipase thermal stability. Since nonionic detergents activate TlL without destabilizing the protein, activation/inhibition and destabilization must be independent processes. We conclude that lipase-detergent interactions occur at many independent levels and are governed by a combination of general and structurally specific interactions. Furthermore, activation of TlL by detergents apparently does not involve the classical interfacial activation phenomenon as monomeric detergent molecules are in most cases responsible for the observed increase in activity. 相似文献
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9.
Sarada Sarkar B. Sreekanth Shreya Kant Rintu Banerjee B. C. Bhattacharyya 《Bioprocess and biosystems engineering》1998,19(1):29-32
Production of lipase by the newly isolated Pseu-domonas species has been optimised. Various parameters like initial pH, temperature, incubation period, effect of agitation, inoculum age, inoculum concentration were optimised. It was observed that modified GYP media with 72 hrs incubation, pH 5.5, at 37?°C in agitation conditions were optimum for growth and production of lipase. While optimising the effect of some additional carbon and nitrogen sources, 7% (v/v) olive oil concentration, and 1% (w/v) mannose were found to be the best. In between prediction of the activities has been done through computer programming. 相似文献
10.
1,2-Ethylene-di-N-n-propylcarbamate (1) is characterized as an essential activator of Pseudomonas species lipase while 1,2-ethylene-di-N-n-butyl-, t-butyl-, n-heptyl-, and n-octyl-carbamates (2-5) are characterized as the pseudo substrate inhibitors of the enzyme in the presence of the detergent taurocholate or triton X-100. The inhibition and activation reactions are more sensitive in taurocholate than in triton X-100. From CD studies, the enzyme changes conformations in the presence of the detergent and further alters conformations by addition of the carbamate activator or inhibitor into the enzyme-detergent adduct. Therefore, this study suggests that the conformational change of lipase during interfacial activation is a continuous process to expose the active site of the enzyme to substrate. From 600 MHz (1)H NMR studies, the conformations of the alpha- and beta-methylene moieties of the activator 1,2-ethylene-di-N-n-propylcarbamate in the presence of substrate change after adding taurocholate into the mixture, and the conformations of the beta-methylene moieties of the inhibitor 1,2-ethylene-di-N-n-butylcarbamate in the presence of substrate alter after adding taurocholate into the mixture. 相似文献
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Triglycerides, oleic acid but not fatty acid-containing, nonionic detergents (Spans, Tweens) were able to stimulate the synthesis
of cell-bound and soluble lipase ofYarrowia lipolytica grown in a complex medium containing citrate and urea. The optimal concentration of olive oil for induction was 0.5% (W/V). The combined effect of a high ionic strength (0.75 mol/L KCl) and of digitonin (2 mmol/L) at pH 7.6 resulted in solubilization
of 80% of the cell-bound lipase and a significant activation of the enzyme. Comparison of twoY. lipolytica strains showed the effects of Mg2+ and Fe3+ concentrations in the medium on the synthesis of the enzyme to be strongly strain-dependent. 相似文献
13.
Grbavčić S Bezbradica D Izrael-Živković L Avramović N Milosavić N Karadžić I Knežević-Jugović Z 《Bioresource technology》2011,102(24):11226-11233
An indigenous Pseudomonas aeruginosa strain has been studied for lipase and protease activities for their potential application in detergents. Produced enzymes were investigated in order to assess their compatibility with several surfactants, oxidizing agents and commercial detergents. The crude lipase appeared to retain high activity and stability in the presence of several surfactants and oxidizing agents and it was insusceptible to proteolysis. Lutensol? XP80 and Triton? X-100 strongly activated the lipase for a long period (up to 40 and 30% against the control after 1h) while the protease activity was enhanced by the addition of Triton? WR1339 and Tween? 80. The washing performance of the investigated surfactants was significantly improved with the addition of the crude enzyme preparation. Studies were further undertaken to improve enzymes production. The optimization of fermentation conditions led to an 8-fold increase of lipase production, while the production of protease was enhanced by 60%. 相似文献
14.
Activation of pancreatic lipase by non-micellar solution of sodium dodecylsulphate (SDS) has been studied. By means of gel-filtration it was found that SDS forces the lipase to form an octamer. A new method of the active sites titration using alkylboronic acids is proposed. The octameric form of the lipase was shown to contain six active sites at the optimal SDS concentration. The activated form of pancreatic lipase supposedly contains six native subunits, each of them forming an active site, and two conformationally altered subunits. This model was confirmed by a probability-theoretic calculation. 相似文献
15.
Aspergillus tamarii Kita grown in media that contained single soluble or insoluble cellulosic sources of carbon, released a complex of cellulolytic enzymes into the medium. The complex was separated into thirteen components by gel filtration followed by ion exchange chromatography. Eight of the components had a high molecular weight and five had a low molecular weight. One of the high molecular weight components, designated Ab, had the character of C1 cellulase enzyme. In a few cases there was synergism between the components, since in combination they liberated more glucose than when alone. 相似文献
16.
Triglycerides, steryl esters, resin acids, free fatty acids and sterols are lipophilic extractives of wood (commonly referred to as pitch or wood resin) and have a negative impact on paper machine runnability and quality of paper. Thus, enzymes capable of modifying these compounds would be potential tools for reducing pitch problems during paper manufacture. In this work, 19 commercial lipase preparations were tested for their ability to degrade steryl esters, which may play a significant role in the formation and stabilisation of pitch particles. Six lipase preparations were shown to be able to degrade steryl esters. Lipase preparations of Pseudomonas sp., Chromobacterium viscosum and Candida rugosa were shown to have the highest steryl esterase activities. The enzymes were able to hydrolyse steryl esters totally in the presence of a surfactant (Thesit). Up to 80% of the steryl esters were degraded in aqueous dispersion. Preliminary characterisation of the enzymatic activities revealed that the lipase preparation of Pseudomonas sp. could be the most potential enzyme in industrial applications. The steryl esterase activity of this preparation was stable over a broad pH range and the enzyme was able to act efficiently at pH 6-10 and at temperatures up to 70 degrees C. 相似文献
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18.
Binding studies of cationic detergents such as cetyl trimethylammonium bromide, Cetylpyridinium bromide and dodecyl trimethylammonium
bromide with lysozyme were carried out by equilibrium dialysis, ultraviolet difference and circular dichroism techniques at
25 C. Binding isotherms at pH 5·0, 7·0 and 9·0 show cooperative binding at all concentrations of detergents and the number
of available binding sites in lysozyme increases with pH. Gibbs free energy of binding calculated on the basis of Wymans’
binding potential concept increases with pH indicating increased binding strength at higher pH. The ultraviolet difference
spectra of the detergent complexes with lysozyme at pH 7·0 and 9·0 in the region of 250–300 nm indicate the involvement of
aromatic amino acid residues as probable binding sites and also the carboxylate groups since the binding is cooperative. The
circular dichroism spectra also indicate the involvement of aromatic amino acid residues in the binding of these detergents.
This is substantiated by the decrease in the intensity of the aromatic positive bands in the near ultraviolet region. The
increase in the magnitude of [θ]222 nm values in the far ultraviolet region with the increase in the concentration of the detergent in the complex indicates conformational
changes resulting in an increase of α-helical content producing a more ordered structure of lysozyme.These binding studies
show that at pH 7·0 and 9·0, hydrophobic interactions play a major role, while at pH 5·0 only electrostatic interactions play
prominent role in the binding of these detergents.
Paper presented at the International Symposium on Biomolecular Structure and Interactions held at the Molecular Biophysics
Unit, Indian Institute of Science, Bangalore, during 17–22, December 1984. 相似文献
19.
将标记有荧光探针FITC(异硫氰基荧光素)的脂肪酶固定化,通过测定活性和荧光光谱,探究各种因素对固定化后荧光标记脂肪酶性质的影响,并分析活性、构象和荧光光谱三者之间的联系。研究结果表明:在固定化脂肪酶过程中,聚乙二醇400二丙烯酸酯能形成合理的网格结构,使酶活较高;配体诱导酶的催化构象,使酶活性提高到未诱导酶的2倍以上;配体抽提能使脂肪酶活性中心得到释放从而提高催化活力。固定化脂肪酶的稳定性大大提高,在90℃、强酸强碱下固定化酶仍保有原酶70%、60%以上的活性;用盐酸胍、脲等溶解变性剂浸泡15d后,酶活性仍然可以保持初始活性的70%以上。荧光光谱能较好地反映脂肪酶的活性和构象变化,最适pH和温度下脂肪酶的荧光强度最低,在溶解变性剂中,荧光强度随时间延长而逐渐降低,这表明不同条件下脂肪酶构象经历的去折叠过程不同。 相似文献
20.
A process was optimized for the enzymatic synthesis of glyceryl ferulate with a yield of up to 96% using a vacuum-rotary evaporation
strategy under following conditions: 15 mmol glycerol, 1.5 mmol ethyl ferulate, 170 mg Candida antarctica lipase, at 60°C for 10 h and under a vacuum of 10 mm Hg. The immobilized lipase can be used 10 times. 相似文献