共查询到20条相似文献,搜索用时 15 毫秒
1.
Mona A. Esawy Yannick Combet-Blanc 《World journal of microbiology & biotechnology》2006,22(3):197-200
Milk-clotting enzyme from Bacillus licheniformis 5A1 was immobilized on Amberlite IR-120 by ionic binding. Almost all the enzyme activity was retained on the support. The
immobilized milk-clotting enzyme was repeatedly used to produce cheese in a batch reactor. The production of cheese was repeated
5 times with no loss of activity. The specific activity calculated on a bound-protein basis was slightly higher than that
of free enzyme. The free and immobilized enzyme were highly tolerant to repeated freezing and thawing. The optimum temperature
for milk-clotting activity was 70 °C with the free enzyme whereas, it was ranged from 70 to 80 °C with the immobilized milk-clotting
enzyme. The activation energy (E
A) of the immobilized milk-clotting enzyme was lower than the free enzyme (E
A = 1.59 and 1.99 Kcal mol−1 respectively). The immobilized milk-clotting enzyme exhibited great thermal stability. The milk-clotting optimum pH was 7.0
for both free and immobilized enzyme. The Michaelis constant K
m of the immobilized milk-clotting enzyme was slightly lower than the free enzyme. 相似文献
2.
Asha Chaubey Rajinder Parshad Pankaj Gupta Subhash C. Taneja Ghulam N. Qazi C.R. Rajan S. Ponrathnam 《Bioorganic & medicinal chemistry》2009,17(1):29-34
Recent reports on immobilization of lipase from Arthrobacter sp. (ABL, MTCC 5125; IIIM isolate) on insoluble polymers have shown altered properties including stability and enantioselectivity. Present work demonstrates a facile method for the preparation of enantiopure β-amino alcohols by modulation of ABL enzyme properties via immobilization on insoluble as well as soluble supports using entrapment/covalent binding techniques. Efficacies of immobilized ABL on insoluble supports prepared from tetraethylorthosilicate/aminopropyltriethoxy silane and soluble supports derived from copolymerization of N-vinyl pyrrolidone-allylglycidyl ether (ANP type)/N-vinyl pyrrolidone-glycidyl methacrylate (GNP type) for kinetic resolution of masked β-amino alcohols have been studied vis-à-vis free ABL enzyme/wet cell biomass. The immobilized lipase on different insoluble/soluble supports has shown 21–110 mg/g protein binding and 30–700 U/g activity for hydrolyzing tributyrin substrate. The findings have shown a significant enhancement in enantioselectivity (ee 99%) vis-à-vis wet cell biomass providing ee 70–90% for resolution of β-amino alcohols. 相似文献
3.
Asha Chaubey Rajinder Parshad Subhash C. Taneja Ghulam N. Qazi 《Process Biochemistry》2009,44(2):154-160
A bacterial lipase from Arthrobacter sp. (ABL: IIIM Jammu, India strain, MTCC No. 5125) has been immobilized on non-magnetic (Type A) and magnetic (Type B) supports derived from copolymerization of 3-aminopropyltriethoxysilane and tetraethylorthosilicate. Immobilized ABL presented 21–34 mg/g protein binding providing 30–75 units/g activity in Type A non-magnetic composites and 24–45 mg/g protein binding providing 35–90 units/g activity with Type B supports containing magnetic particles. Immobilized ABL preparations have shown enhanced stability at pH 5–9 and temperature up to 70 °C whereas free ABL is unstable under these conditions. Improved hydrolytic conversion as well as enantioselectivity were observed with acyl fluoxetine intermediate (ethyl 3-hydroxy-3-phenylpropanoate alkyl acylates) and chiral auxiliaryacyl 1-phenyl ethanol using immobilized ABL derivatives (ee ~99%; 3–4-fold increase in E-values) as compared to ABL enzyme/cells (ee 93–98%). Introduction of magnetic particles in these supports has led to easier separation process with high product recovery yields. 相似文献
4.
Purification, immobilization and characterization of linoleic acid isomerase on modified palygorskite 总被引:2,自引:0,他引:2
Linoleic acid isomerase from Lactobacillus delbrueckii subsp. bulgaricus 1.1480 was purified by DEAE ion-exchange chromatography and gel filtration chromatography. An overall 5.1% yield and purification
of 93-fold were obtained. The molecular weight of the purified protein was ~41 kDa which was analyzed by SDS-PAGE. The purified
enzyme was immobilized on palygorskite modified with 3-aminopropyltriethoxysilane. The immobilized enzyme showed an activity
of 82 U/g. The optimal temperature and pH for the activity of the free enzyme were 30 °C and pH 6.5, respectively; whereas
those for the immobilized enzyme were 35 °C and pH 7.0, respectively. The immobilized enzyme was more stable than the free
enzyme at 30–60 °C, and the operational stability result showed that more than 85% of its initial activity was retained after
incubation for 3 h. The K
m and V
max values of the immobilized enzyme were found to be 0.0619 mmol l−1 and 0.147 mmol h−1 mg−1, respectively. The immobilized enzyme had high operational stability and retained high enzymatic activity after seven cycles
of reuse at 37 °C. 相似文献
5.
Summary Xylanase from Scytalidium thermophilum was immobilized on Eudragit L-100, a pH sensitive copolymer of methacrylic acid and methyl methacrylate. The enzyme was non-covalently
immobilized and the system expressed 70% xylanase activity. The immobilized preparation had broader optimum temperature of
activity between 55 and 65 °C as compared to 65 °C in case of free enzyme and broader optimum pH between 6.0 and 7.0 as compared
to 6.5 in case of free enzyme. Immobilization increased the t1/2 of enzyme at 60 °C from 15 to 30 min with a stabilization factor of 2. The Km and Vmax values for the immobilized and free xylanase were 0.5% xylan and 0.89 μmol/ml/min and 0.35% xylan and 1.01 μmol/ml/min respectively. An Arrhenius plot showed an increased value of activation energy for immobilized xylanase (227 kcal/mol)
as compared to free xylanase (210 kcal/mol) confirming the higher temperature stability of the free enzyme. Enzymatic saccharification
of xylan was also improved by xylanase immobilization. 相似文献
6.
Ginka Delcheva Georgi Dobrev Ivan Pishtiyski 《Journal of Molecular Catalysis .B, Enzymatic》2008,54(3-4):109-115
The dynamics of β-xylosidase biosynthesis from Aspergillus niger B 03 was investigated in laboratory bioreactor. Maximum xylosidase activity 5.5 U/ml was achieved after 80 h fermentation at medium pH 4.0. The isolated β-xylosidase was immobilized on polyamide membrane support and the basic characteristics of the immobilized enzyme were determined. Maximum immobilization and activity yield obtained was 30.0 and 6.8%, respectively. A shift in temperature optimum and pH optimum was observed for immobilized β-xylosidase compared to the free enzyme. Immobilized enzyme exhibited maximum activity at 45 °C and pH 4.5 while its free counterpart at 70 °C and pH 3.5, respectively. Thermal stability at 40 and 50 °C and storage stability of immobilized β-xylosidase were investigated at pH 5.0. Kinetic parameters Km, Vmax and Ki were determined for both enzyme forms. Free and immobilized β-xylosidase were tested for xylose production from birchwood xylan. The substrate was preliminarily depolymerized with xylanase to xylooligosaccharides and the amount of xylose obtained after their hydrolysis with free and immobilized β-xylosidase was determined by HPLC analysis. Continuous enzyme hydrolysis of birchwood xylan was performed with xylanase and free or immobilized β-xylosidase. The maximum extent of hydrolysis was 25 and 30% with free and immobilized enzyme, respectively. Immobilized preparation was also examined for reusability in 20 consecutive cycles at 40 °C. 相似文献
7.
A new method for immobilization of acetylcholinesterase (AChE) to alginate gel beads by activating the carbonyl groups of
alginate using carbodiimide coupling agent has been successfully developed. Maximum reaction rate (V
max) and Michaelis–Menten constant (K
m) were determined for the free and binary immobilized enzyme. The effects of pH, temperature, storage stability, reuse number
and thermal stability on the free and immobilized AChE were also investigated. For the free and binary immobilized enzyme
on the Ca–alginate gel beads, optimum pH values were found to be 7 and 8, respectively. Optimum temperatures for the free
and immobilized enzyme were observed to be 30 and 35 °C, respectively. Upon 60 days of storage the preserved activity of free
and immobilized enzyme were found as 4 and 68%, respectively. In addition, reuse number, and thermal stability of the free
AChE were increased by as a result of binary immobilization. 相似文献
8.
L. Mojovic Z. Knezevic R. Popadic S. Jovanovic 《Applied microbiology and biotechnology》1998,50(6):676-681
Lipase from Candida rugosa was immobilized by adsorption onto a macroporous copolymer support. Under optimum conditions the maximum amount of protein
bound was 15.4 mg/g and the immobilization efficiency was 62%. The kinetics of lipase binding to the selected polymer carrier
was assessed by using a general model of topochemical reactions. The effect of temperature on adsorption was thoroughly investigated,
as was the adsorption mechanism itself. Analysis of the proposed kinetic model and the specific kinetic parameters measured
suggest that surface kinetics control the adsorption process. According to the activation energy (E
a) and the rate constant, k, the enzyme has rather a high affinity for the support's active sites. The immobilized enzyme was used to catalyse the hydrolysis
of palm oil in a lecithin/isooctane reaction system, in which the enzyme's activity was 70% that of the free enzyme. Kinetic
parameters such as maximum velocity (V
max) and the Michaelis constant (K
m) were determined for the free and the immobilized lipase. Following repeated use, the immobilized lipase retained 56% of
its initial activity after the fifth hydrolysis cycle.
Received: 3 April 1998 / Received revision: 28 July 1998 / Accepted: 29 July 1998 相似文献
9.
Sareeta Nahakpam Puneeta Singh Kavita Shah 《Biotechnology and Bioprocess Engineering》2008,13(5):632-638
The direct immobilization of soluble peroxidase isolated and partially purified from shoots of rice seedlings in calcium alginate
beads and in calcium agarose gel was carried out. Peroxidase was assayed for guaiacol oxidation products in presence of hydrogen
peroxide. The maximum specific activity and immobilization yield of the calcium agarose immobilized peroxidase reached 2,200
U mg−1 protein (540 mU cm−3 gel) and 82%, respectively. In calcium alginate the maximum activity of peroxidase upon immobilization was 210 mU g−1 bead with 46% yield. The optimal pH for agarose immobilized peroxidase was 7.0 which differed from the pH 6.0 for soluble
peroxidase. The optimum temperature for the agarose immobilized peroxidase however was 30°C, which was similar to that of
soluble peroxidase. The thermal stability of calcium agarose immobilized peroxidase significantly enhanced over a temperature
range of 30∼60°C upon immobilization. The operational stability of peroxidase was examined with repeated hydrogen peroxide
oxidation at varying time intervals. Based on 50% conversion of hydrogen peroxide and four times reuse of immobilized gel,
the specific degradation of guaiacol for the agarose immobilized peroxidase increased three folds compared to that of soluble
peroxidase. Nearly 165% increase in the enzyme protein binding to agarose in presence of calcium was noted. The results suggest
that the presence of calcium, ions help in the immobilization process of peroxidase from rice shoots and mediates the direct
binding of the enzyme to the agarose gel and that agarose seems to be a better immobilization matrix for peroxidase compared
to sodium alginate. 相似文献
10.
Thermomucor indicae-seudaticae was immobilized in alginate, κ-carrageenan, agarose, agar, polyacrylamide and loofah (Luffa cylindrica) sponge (as such or coated with alginate/starch/Emerson YpSs agar), and used for the production of glucoamylase in submerged
fermentation. The mycelium developed from alginate-immobilized sporangiospores secreted higher glucoamylase titres (22.7 U ml−1) than those immobilized in other gel matrices and the freely growing mycelial pellets (18.5 U ml−1). Loofah network provided a good support for mycelial growth, but the enzyme production was lower than that attained with
alginate beads. Glucoamylase production increased with inoculum density and the optimum levels were achieved when 40 calcium
alginate beads (∼5 × 106 immobilized spores) were used to inoculate 50 ml production medium. The alginate bead inoculum displayed high storage stability
at 4°C and produced comparable enzyme titres up to 120 days. The glucoamylase production by hyphae emerged from the immobilized
sporangiospores was almost stable over eight batches of repeated fermentation. Scanning electron micrographs of alginate beads,
after batch fermentation, revealed extensive mycelial growth inside and around the beads. 相似文献
11.
Guang Yang Jianping Wu Gang Xu Lirong Yang 《Journal of Molecular Catalysis .B, Enzymatic》2009,57(1-4):96-103
Lipase from Arthrobacter sp. was immobilized onto low-cost diatomite materials using different protocols for the resolution of 4-hydroxy-3-methyl-2-(2-propenyl)-2-cyclopenten-1-one (HMPC) by asymmetric acylation. The support surface was grafted various functional groups including methacryloxypropyl, vinyl, octyl, dodecyl and γ-(aminopropyl)-glutaraldehyde. These modifications resulted in various mechanisms during the immobilization and thus introduced different characteristics to the prepared lipases. The interfacially adsorbed lipase onto dodecyl-modified support exhibited both higher activity and stability among these immobilized preparations. The modified enzyme-aggregate coating method was performed based on interfacial adsorption in our work, and the characteristics of this immobilized lipase were investigated and compared with those by cross-linking and interfacial adsorption methods. It was shown that the enzyme-aggregate coated lipase yielded the highest activity with a recovered activity of 8.5-fold of the free enzyme, and the highest operational stability with 85% of initial activity remained after 10 recycles. Excellent enantioselectivity (E ≥ 400, with e.e. = 99% of S-HMPC) was obtained for most lipase preparations in our paper (E = 85 for the free enzyme). 相似文献
12.
Z.T. Xing J.H. Cheng Q. Tan Y.J. Pan 《World journal of microbiology & biotechnology》2006,22(8):799-806
Summary Extracellular laccase in cultures of Grifola frondosa grown in liquid culture on a defined medium was first detectable in the early/middle stages of primary growth, and enzyme activity continued to increase even after fungal biomass production had peaked. Laccase production was significantly increased by supplementing cultures with 100–500 (M Cu over the basal level (1.6 mM Cu) and peak levels observed at 300 mM Cu were ∼
∼7-fold higher than in unsupplemented controls. Decreased laccase activity similar to levels detected in unsupplemented controls, as well as an adverse effect on fungal growth, occurred with further supplementation up to and including 0.9 mM Cu, but higher enzyme titres (2- to 16-fold compared with controls) were induced in cultures supplemented with 1–2 mM Cu2+. SDS-PAGE combined with activity staining revealed the presence of a single protein band (M
r ∼
∼70 kDa) exhibiting laccase activity in control culture fluids, whereas an additional distinct second laccase protein band (M
r␣∼
∼45 kDa) was observed in cultures supplemented with 1–2 mM Cu. Increased levels of extracellular laccase activity, and both laccase isozymes, were also detected in cultures of G. frondosa supplemented with ferulic, vanillic, veratric and 4-hydroxybenzoic acids, and 4-hydroxybenzaldehyde. The optimal temperature and pH values for laccase activity were 65 °C and pH 2.2 (using 2,2′-azinobis(3-ethylbenzthiazoline-6-sulfonate) {ABTS} as substrate), respectively, and the enzyme was relatively heat stable. In solid-state cultures of G. frondosa grown under conditions adopted for industrial-scale mushroom production, extracellular laccase levels increased during the substrate colonization phase, peaked when the substrate was fully colonized, and then decreased sharply during fruit body development. 相似文献
13.
Pectinase was immobilized onto thermo-sensitive amphiphilic block copolymers poly(styrene-b-Nisopropylacrylamide) PS-b-poly(N-isopropylacrylamide) (PNIPAM) by covalent attachment. Biochemical studies have found that the stability of the PS-b-PNIPAM support is not impeded by the bound proteins despite that up to 242.5 mg of enzyme is immobilized per gram of carrier
particles. The immobilized enzyme retained nearly 65% of its initial activity over 30 days, and the optimum temperature and
pH also increased to the range of 60 ∼ 70°C and 4.0 ∼ 6.0, respectively. The immobilized enzyme also exhibited great operational
stability, and more than 60% residual activity was observed in the immobilized enzyme after 10 batch reactions. Moreover,
the lower critical solution temperature of the PS-b-PNIPAM support could be switched on or off by a small change in solution temperature. Thus, the immobilized pectinase could
be recovered and showed durable activity during the recycle process. 相似文献
14.
Trigonopsis variabilis induced for D-amino acid oxidase and catalase was immobilized by entrapment in Polyacrylamide beads obtained by radiation
polymerisation. Permeabilization of the cells was found to be essential for optimal activity of the enzymes in free cells.
However, the process of entrapment itself was found to eliminate the permeability barrier of cells immobilized in Polyacrylamide.
The two enzymes exhibited a differential response on Polyacrylamide entrapment. Thus, D-amino acid oxidase activity was stabilized
to heat inactivation whereas catalase in the same cells showed a destabilization on entrapment in Polyacrylamide. The coimmobilized
enzyme preparation showed an operational half life of 7–9 days after which the D-amino acid oxidase activity remained stable
at a value 35–40% of that of the initial activity for a study period of 3 weeks. Coimmobilization of MnO2 was not effective in enhancing the operational life of the enzyme preparation. 相似文献
15.
Vania Castriani Fernandes da Silva Fabiano Jares Contesini Patrícia de Oliveira Carvalho 《Journal of industrial microbiology & biotechnology》2009,36(7):949-954
Considering the extraordinary microbial diversity and importance of fungi as enzyme producers, the search for new biocatalysts
with special characteristics and possible applications in biocatalysis is of great interest. Here, we report the performance
in the resolution of racemic ibuprofen of a native enantioselective lipase from Aspergillus niger, free and immobilized in five types of support (Accurel EP-100, Amberlite MB-1, Celite, Montmorillonite K10 and Silica gel).
Amberlite MB-1 was found to be the best support, with a conversion of 38.2%, enantiomeric excess of 50.7% and enantiomeric
ratio (E value) of 19 in 72 h of reaction. After a thorough optimization of several parameters, the E value of the immobilized Aspergillus niger lipase was increased (E = 23) in a shorter reaction period (48 h) at 35°C. Moreover, the immobilized Aspergillus niger lipase maintained an esterification activity of at least 80% after 8 months of storage at 4°C and could be reused at least
six times. 相似文献
16.
Soria F Ellenrieder G Oliveira GB Cabrera M Carvalho LB 《Applied microbiology and biotechnology》2012,93(3):1127-1134
α-l-Rhamnosidase from Aspergillus terreus was covalently immobilized on the following ferromagnetic supports: polyethylene terephthalate (Dacron-hydrazide), polysiloxane/polyvinyl
alcohol (POS/PVA), and chitosan. The powdered supports were magnetized by thermal coprecipitation method using ferric and
ferrous chlorides, and the immobilization was carried out via glutaraldehyde. The activity of the Dacron-hydrazide (0.53 nkat/μg
of protein) and POS/PVA (0.59 nkat/μg of protein) immobilized enzyme was significantly higher than that found for the chitosan
derivative (0.06 nkat/μg of protein). The activity–pH and activity–temperature profiles for all immobilized enzymes did not
show difference compared to the free enzyme, except the chitosan derivative that presented higher maximum temperature at 65 °C.
The Dacron-hydrazide derivative thermal stability showed a similar behavior of the free enzyme in the temperature range of
40–70 °C. The POS/PVA and chitosan derivatives were stable up to 60 °C, but were completely inactivated at 70 °C. The activity
of the preparations did not appreciably decrease after ten successive reuses. Apparent K
m of α-l-rhamnosidase immobilized on magnetized Dacron-hydrazide (1.05 ± 0.22 mM), POS/PVA (0.57 ± 0.09 mM), and chitosan (1.78 ± 0.24 mM)
were higher than that estimated for the soluble enzyme (0.30 ± 0.03 mM). The Dacron-hydrazide enzyme derivative showed better
performance than the free enzyme to hydrolyze 0.3% narigin (91% and 73% after 1 h, respectively) and synthesize rhamnosides
(0.116 and 0.014 mg narirutin after 1 h, respectively). 相似文献
17.
Jack bean urease (urea aminohydrolase, E.C. 3.5.1.5) was entrapped into chitosan–alginate polyelectrolyte complexes (C-A PEC) and poly(acrylamide-co-acrylic acid)/κ-carrageenan (P(AAm-co-AA)/carrageenan) hydrogels for the potential use in immobilization of urease, not previously reported. The effects of pH, temperature, storage stability, reuse number, and thermal stability on the free and immobilized urease were examined. For the free and immobilized urease into C-A PEC and P(AAm-co-AA)/carrageenan, the optimum pH was found to be 7.5 and 8, respectively. The optimum temperature of the free and immobilized enzymes was also observed to be 55 and 60 °C, respectively. Michaelis–Menten constant (K
m) values for both immobilized urease were also observed smaller than free enzyme. The storage stability values of immobilized enzyme systems were observed as 48 and 70%, respectively, after 70 days. In addition to this, it was observed that, after 20th use in 5 days, the retained activities for immobilized enzyme into C-A PEC and P(AAm-co-AA)/carrageenan matrixes were found as 55 and 89%, respectively. Thermal stability of the free urease was also increased by a result of immobilization. 相似文献
18.
U. C. Banerjee 《Folia microbiologica》1992,37(4):256-260
β-Glucosidase fromCurvularia lunata was immobilized in pellets of polyacrylamide, sodium alginate and agar. The activity of the enzyme was estimated at different
times by measuring the absorbance of a solution into which 2-nitrophenol was released by the enzyme. The effect of pH and
temperature was studied to select the optimum conditions. Thermostability of the β-glucosidase in each of the carriers was
assessed over a period of 12–26 d. The immobilized enzyme on all the three carriers retained its activity longer than free
enzyme did. Polyacrylamide was the best carrier both in terms of thermostability and of reusability of the immobilized enzyme
preparations. The Michaelis constant (K
m) for each of the immobilized enzyme preparation was calculated. 相似文献
19.
A strong fibrin-specific fibrinolytic enzyme was purified from the cell-free spent culture broth of a thermophilic organism,
Streptomyces megasporus SD5. The strain could produce 150 mg crude protein per litre of spent broth, with a specific activity of 80 IU (Plough units)
per milligram, within 18 h of incubation at 55 °C in glucose yeast/extract/peptone (GYP) medium, pH 8.0. For production of
the enzyme, the strain could utilize different carbon and nitrogen sources with a C:N ratio of ∼ 1:2. The enzyme was stable
at a broad range of pH ranging from 5 to 9, and highly thermostable with 50% activity after storage at 60 °C for 6 months.
The enzyme belonged to the serine endopeptidase group. In vitro clot lysis revealed that the enzyme was active at 37 °C.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
20.
Jeyagowri Kiddinamoorthy Alfredo J. Anceno Gulelat D. Haki Sudip K. Rakshit 《World journal of microbiology & biotechnology》2008,24(5):605-612
Production of extracellular xylanase from Bacillus sp. GRE7 using a bench-top bioreactor and solid-state fermentation (SSF) was attempted. SSF using wheat bran as substrate
and submerged cultivation using oat-spelt xylan as substrate resulted in an enzyme productivity of 3,950 IU g−1 bran and 180 IU ml−1, respectively. The purified enzyme had an apparent molecular weight of 42 kDa and showed optimum activity at 70°C and pH
7. The enzyme was stable at 60–80°C at pH 7 and pH 5–11 at 37°C. Metal ions Mn2+ and Co2+ increased activity by twofold, while Cu2+ and Fe2+ reduced activity by fivefold as compared to the control. At 60°C and pH 6, the K
m for oat-spelt xylan was 2.23 mg ml−1 and V
max was 296.8 IU mg−1 protein. In the enzymatic prebleaching of eucalyptus Kraft pulp, the release of chromophores, formation of reducing sugars
and brightness was higher while the Kappa number was lower than the control with increased enzyme dosage at 30% reduction
of the original chlorine dioxide usage. The thermostability, alkali-tolerance, negligible presence of cellulolytic activity,
ability to improve brightness and capacity to reduce chlorine dioxide usage demonstrates the high potential of the enzyme
for application in the biobleaching of Kraft pulp. 相似文献