共查询到20条相似文献,搜索用时 15 毫秒
1.
Soybean seed coat peroxidase (SBP) was immobilized on various polyaniline-based polymers (PANI), activated with glutaraldehyde. The most reduced polymer (PANIG2) showed the highest immobilization capacity (8.2 mg SBP?g?1 PANIG2). The optimum pH for immobilization was 6.0 and the maximum retention was achieved after a 6-h reaction period. The efficiency of enzyme activity retention was 82%. When stored at 4°C, the immobilized enzyme retained 80% of its activity for 15 weeks as evidenced by tests performed at 2-week intervals. The immobilized SBP showed the same pH-activity profile as that of the free SBP for pyrogallol oxidation but the optimum temperature (55°C) was 10°C below that of the free enzyme. Kinetic analysis show that the Km was conserved while the specific Vmax dropped from 14.6 to 11.4 µmol min?1 µg?1, in agreement with the immobilization efficiency. Substrate specificity was practically the same for both enzymes. Immobilized SBP showed a greatly improved tolerance to different organic solvents; while free SBP lost around 90% of its activity at a 50% organic solvent concentration, immobilized SBP underwent only 30% inactivation at a concentration of 70% acetonitrile. Taking into account that immobilized HRP loses more than 40% of its activity at a 20% organic solvent concentration, immobilized SBP performed much better than its widely used counterpart HRP. 相似文献
2.
Mucor miehei lipase was immobilized on magnetic polysiloxane-polyvinyl alcohol particles by covalent binding. The resulting immobilized biocatalyst was recycled by seven assays, with a retained activity around 10% of its initial activity. Km and Vmax were respectively 228.3 M and 36.1 U mg of protein–1 for immobilized enzyme. Whereas the optimum temperature remained the same for both soluble and immobilized lipase (45 °C), there was a shift in pH profiles after immobilization. Optimum pH for the immobilized lipase was 8.0. Immobilized enzyme showed to be more resistant than soluble lipase when assays were performed out of the optimum temperature or pH. 相似文献
3.
《Biocatalysis and Biotransformation》2013,31(6):278-287
AbstractGlycerol dehydrogenase (GlyDH) which oxidizes glycerol to the value-added chemical, 1,3-dihydroxyacetone, is of interest due to the oversupply of glycerol as a by-product of the biodiesel industry. To exploit the enzymatic oxidation of glycerol industrially, silica coated magnetic Fe3O4 nanoparticles were prepared and then activated with an amino-silane reagent for covalent immobilization of GlyDH via a glutaraldehyde linkage. At the optimal glutaraldehyde concentration of 0.05% (v/v), an enzyme loading of up to 57.5 mg/g-nanoparticles was achieved with 81.1% of the original activity retained. Reaction kinetic analysis indicated that the immobilized GlyDH had almost the same Michaelis-Menten constants for both NAD+ and glycerol as the free GlyDH did. However, after immobilization the turnover number kcat of the GlyDH decreased from 164 s?1 to 113 s?1, and the reaction was 1.3-fold less sensitive to inhibition by DHA, which could compensate the decrease in kcat. The immobilized GlyDH was also less sensitive to changes in pH and temperature, and showed a 5.3-fold improvement in thermal stability at 50°C. Furthermore, excellent reusability was observed such that 10 cycles of re-use only led to 9% loss of enzyme activity. 相似文献
4.
Saptadip Samanta Malabendu Jana Chiranjit Maity Sanjay Kar Pradeep K. Das Mohapatra Bikas R. Pati 《Biocatalysis and Biotransformation》2013,31(2):131-135
Purified α-amylase from a soil bacterium Bacillus sp. SKB4 was immobilized on coconut coir, an inexpensive cellulosic fiber, with the cross-linking agent glutaraldehyde. The catalytic properties and stability of the immobilized enzyme were compared with those of its soluble form. The enzyme retained 97.2% of its activity and its catalytic properties were not drastically altered after immobilization. The pH optimum and stability of the immobilized enzyme were shifted towards the alkaline range compared to the free enzyme. The optimum temperature for enzymatic activity was 90°C in both forms of the enzyme. The soluble and immobilized enzyme retained 19% and 70% of original activity, respectively, after pre-incubation for 1 h at 90°C. Immobilized amylase was less susceptible to attack by heavy metal ions and showed higher Km and Vmax values than its free form. The bound enzyme showed significant activity and stability after 6 months of storage at 4°C. All of these characteristics make the new carrier system suitable for use in the bioprocess and food industries. 相似文献
5.
《Biocatalysis and Biotransformation》2013,31(5-6):314-326
AbstractPolyamine microspheres (PA-M) prepared using polyethyleneimine as matrix were used for the immobilization of Candida antarctica lipase. The isoelectric point of PA-M is 10.6, and the hydrophobicity of PA-M was indicated using naphthalene. Optimization of conditions showed that the maximal loading of lipase on PA-M reached 230.2 mg g? 1 at pH 9.0 and 35°C. An increased buffer concentration had no effect on the activity of lipase but decreased the amount of lipase adsorbed. Simulation with Langmuir and Freundlich isotherms demonstrated that the adsorption of lipase on PA-M was thermodynamically favorable. Covalent crosslinking of the lipase adsorbed extended the pH range and increased the optimal temperature of the lipase activity. The physically adsorbed lipase (P-lipase) and the covalently immobilized derivative (C-lipase) retained more than 75% and 85% of their initial activity, respectively, after 10 cycles of usage. The half-lives of P-lipase and C-lipase at 50°C were 15.70 and 27.67 times higher than that of the free enzyme, respectively. Compared to P-lipase, covalent immobilization obviously reduced the catalytic efficiency and activation energy of the enzyme. 相似文献
6.
Sanjay K. S. Patel Rahul K. Gupta Sang-Yong Kim In-Won Kim Vipin C. Kalia Jung-Kul Lee 《Indian journal of microbiology》2021,61(1):45
In the present study, Rhus vernicifera laccase (RvLac) was immobilized through covalent methods on the magnetic nanoparticles. Fe2O3 and Fe3O4 nanoparticles activated by 3-aminopropyltriethoxysilane followed with glutaraldehyde showed maximum immobilization yields and relative activity up to 81.4 and 84.3% at optimum incubation and pH of 18 h and 5.8, respectively. The maximum RvLac loading of 156 mg/g of support was recorded on Fe2O3 nanoparticles. A higher optimum pH and temperature of 4.0 and 45 °C were noted for immobilized enzyme compared to values of 3.5 and 40 °C for free form, respectively. Immobilized RvLac exhibited better relative activity profiles at various pH and temperature ranges. The immobilized enzyme showed up to 16-fold improvement in the thermal stability, when incubated at 60 °C, and retained up to 82.9% of residual activity after ten cycles of reuses. Immobilized RvLac exhibited up to 1.9-fold higher bisphenol A degradation efficiency potential over free enzyme. Previous reports have demonstrated the immobilization of RvLac on non-magnetic supports. This study has demonstrated that immobilization of RvLac on magnetic nanoparticles is very efficient especially for achieving high loading, better pH and temperature profiles, and thermal- and solvents-stability, high reusability, and higher degradation of bisphenol A. 相似文献
7.
Adriano A. Mendes Bruno C. M. Barbosa Maria L. C. P. Da Silva 《Biocatalysis and Biotransformation》2013,31(5):393-400
Zirconium phosphate (ZrP), a low-cost inorganic material with well-defined physicochemical properties, was successfully used as support for immobilizing Candida rugosa lipase by covalent bonding. The immobilized derivative showed high catalytic activity in both aqueous and non-aqueous media. Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy measurements demonstrated that the ZrP fulfilled the morphological requirements for use as a matrix for immobilizing lipases. The free and immobilized lipases were compared in terms of pH, temperature and thermal stability. The immobilized lipase had a higher pH optimum (7.5) and higher optimum temperature (50°C) than the free lipase. Immobilization also increased the thermal stability. The hydrolysis of p-nitrophenyl palmitate (pNPP) by immobilized lipase, examined at 37°C, followed Michaelis–Menten kinetics. Values for Km=1.18 µM and Vmax=325Umg?1 indicated that the immobilized system was subject to mass transfer limitations. The immobilized derivative was also tested under repetitive reaction batches in both ester hydrolysis and synthesis. 相似文献
8.
The characterization of the hydrogel was performed using Fourier‐transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscopy. Purified Bacillus pumilus Y7‐derived alkaline protease was immobilized in Poly (vinylimidazole)/clay (PVI/SEP) hydrogel with 95% yield of immobilization. Immobilization decreased the pH optimum from 9 to 6 for free and immobilized enzyme, respectively. Temperature optimum 3°C decreased for immobilized enzyme. The Km, Vm, and kcat of immobilized enzyme were 4.4, 1.7, and 7.5‐fold increased over its free counterpart. Immobilized protease retained about 65% residual activity for 16th reuse. The immobilized protease endured its 35% residual activity in the material after six cycle's batch applications. The results of thermodynamic analysis for casein hydrolysis showed that the ΔG≠ (activation free energy) and ΔG≠E‐T (activation free energy of transition state formation) obtained for the immobilized enzyme decreased in comparison to those obtained for the free enzyme. On the other hand, the value of ΔG≠ES (free energy of substrate binding) was observed to have increased. These results indicate an increase in the spontaneity of the biochemical reaction post immobilization. Enthalpy value of immobilized enzyme that was 2.2‐fold increased over the free enzyme indicated lower energy for the formation of the transition state, and increased ΔS≠ value implied that the immobilized form of the enzyme was more ordered than its free form. 相似文献
9.
Sushil Nagar Anuradha Mittal Davender Kumar Lalit Kumar Vijay Kumar Gupta 《Process Biochemistry》2012,47(9):1402-1410
This paper reports covalent immobilization of xylanase by response surface methodology on glutaraldehyde-activated aluminum oxide pellets. The optimization of process parameters gave an immobilization yield of 83.65%. The bound enzyme displayed increase in optimum temperature (from 50 to 60 °C) and Vmax (from 3333.33 to 5000 IU/mL) in comparison with free enzyme. The pH and temperature stability were also enhanced. An observed increase in half-lives and D-values resulted in improved thermostability. Thermodynamically, increase in enthalpy and free energy change after covalent immobilization could be credited to the enhanced stability. Immobilized xylanase could be reused for 10 consecutive cycles retaining 60% of its initial activity. It was found to be effective in releasing reducing sugar from poultry feed. Immobilization on aluminum oxide pellets is important due to their mechanical resistance at high pH and temperature. So, considerable stability and reusability of bound enzyme may be advantageous for its industrial application. 相似文献
10.
Extracellular exoinulinase from Kluyveromyces marxianus YS-1, which hydrolyzes inulin into fructose, was immobilized on Duolite A568 after partial purification by ethanol precipitation
and gel exclusion chromatography on Sephadex G-100. Optimum temperature of immobilized enzyme was 55 °C, which was 5 °C higher
than the free enzyme and optimal pH was 5.5. Immobilized biocatalyst retained more than 90% of its original activity after
incubation at 60 °C for 3 h, whereas in free form its activity was reduced to 10% under same conditions, showing a significant
improvement in the thermal stability of the biocatalyst after immobilization. Apparent K
m values for inulin, raffinose and sucrose were found to be 3.75, 28.5 and 30.7 mM, respectively. Activation energy (E
a) of the immobilized biocatalyst was found to be 46.8 kJ/mol. Metal ions like Co2+ and Mn2+ enhanced the activity, whereas Hg2+ and Ag2+ were found to be potent inhibitors even at lower concentrations of 1 mM. Immobilized biocatalyst was effectively used in
batch preparation of high fructose syrup from Asparagus racemosus raw inulin and pure inulin, which yielded 39.2 and 40.2 g/L of fructose in 4 h; it was 85.5 and 92.6% of total reducing sugars
produced, respectively. 相似文献
11.
Sanjay Mohan Gupta Supriya Gupta Anil Kumar 《Journal of plant biochemistry and biotechnology.》2009,18(1):113-116
Cellulase extracted from seeds of Cowpea (Vigna sinensis L var VITA-4) was partially purified and immobilized on brick dust as solid support via glutaraldehyde. The percentage retention of the enzyme activity on brick dust was nearly 85%. After immobilization specific activity of the enzyme increased from 0.275 to 0.557 U mg?1 protein with about 2 fold enrichment. The optimum pH and temperature of soluble enzyme were determined as pH 4.6 and WC, respectively whereas immobilized enzyme showed at pH 5.0 and 37°C, respectively. The Vmax values for soluble and immobilized enzyme were determined as 6.67 and 1.25 mg min?1, respectively whereas Km values were 4.35 and 4.76 mg ml?1, respectively. The immobilized enzyme displayed higher thermal stability than soluble enzyme and retained about 50% of its initial activity after 12 reuses. Immobilized enzyme was packed in an indigenously designed double walled glass bed reactor for continuous production of reducing sugars. 相似文献
12.
Silanized palygorskite for lipase immobilization 总被引:2,自引:0,他引:2
Jianhua Huang Yuanfa Liu Xingguo Wang 《Journal of Molecular Catalysis .B, Enzymatic》2009,57(1-4):10-15
Lipase from Candida lipolytica has been immobilized on 3-aminopropyltriethoxysilane-modified palygorskite support. Scanning electron micrographs proved the covalently immobilization of C. lipolytica lipase on the palygorskite support through glutaraldehyde. Using an optimized immobilization protocol, a high activity of 3300 U/g immobilized lipase was obtained. Immobilized lipase retained activity over wider ranges of temperature and pH than those of the free enzyme. The optimum pH of the immobilized lipase was at pH 7.0–8.0, while the optimum pH of free lipase was at 7.0. The retained activity of the immobilized enzyme was improved both at lower and higher pH in comparison to the free enzyme. The immobilized enzyme retained more than 70% activity at 40 °C, while the free enzyme retained only 30% activity. The immobilization stabilized the enzyme with 81% retention of activity after 10 weeks at 30 °C whereas most of the free enzyme was inactive after a week. The immobilized enzyme retains high activity after eight cycles. The kinetic constants of the immobilized and free lipase were also determined. The Km and Vmax values of immobilized lipase were 0.0117 mg/ml and 4.51 μmol/(mg min), respectively. 相似文献
13.
Immobilization of Bacillus licheniformis
l-arabinose isomerase (BLAI) on aminopropyl glass modified with glutaraldehyde (4 mg protein g support−1) was found to enhance the enzyme activity. The immobilization yield of BLAI was proportional to the quantity of amino groups
on the surface of support. Reducing particle size increased the adsorption capacity (q
m) and affinity (k
a). The pH and temperature for immobilization were optimized to be pH 7.1 and 33°C using response surface methodology (RSM).
The immobilized enzyme was characterized and compared to the free enzyme. There is no change in optimal pH and temperature
before and after immobilization. However, the immobilized BLAI enzyme achieved 145% of the activity of the free enzyme. Correspondingly,
the catalytic efficiency (k
cat/K
m) was improved 1.47-fold after immobilization compared to the free enzyme. The thermal stability was improved 138-fold (t
1/2 increased from 2 to 275 h) at 50°C following immobilization. 相似文献
14.
《Enzyme and microbial technology》1987,9(9):550-552
A simple procedure for the immobilization of β-amylase (EC3.2.1.2) on IR-120 Al3+ is described. Immobilization brought about a slight shift in the optimum pH towards the alkaline side relative to that of the soluble enzyme. Immobilized β-amylase showed a broader temperature optima (45–55°C) compared with the soluble enzyme (45°C). A six-fold increase in the Km was also noticed. On storage and repeated use the immobilized enzyme retained approximately 60% of its initial activity up to 120 days at room temperature. 相似文献
15.
K. Naganagouda S. J. Prashanth S. K. Shankar S. K. Dhananjay V. H. Mulimani 《World journal of microbiology & biotechnology》2007,23(8):1131-1137
Raffinose oligosaccharides (RO) are the major factors responsible for flatulence following ingestion of soybean-derived products.
Removal of RO from seeds or soymilk would then have a positive impact on the acceptance of soy-based foods. In this study,
α-galactosidase from Aspergillus oryzae was entrapped in gelatin using formaldehyde as the hardener. The immobilization yield was 64.3% under the optimum conditions
of immobilization. The immobilized α-galactosidase showed a shift in optimum pH from 4.8 to 5.4 in acetate buffer. The optimum
temperature also shifted from 50°C to 57°C compared with soluble enzyme. Immobilized α-galactosidase was used in batch, repeated
batch and continuous mode to degrade RO present in soymilk. In the repeated batch, 45% reduction of RO was obtained in the
fourth cycle. The performance of immobilized α-galactosidase was tested in a fluidized bed reactor at different flow rates
and 86% reduction of RO in soymilk was obtained at 25 ml h−1 flow rate. The study revealed that immobilized α-galactosidase in continuous mode is efficient in reduction of RO present
in soymilk. 相似文献
16.
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
17.
《Journal of Fermentation Technology》1987,65(2):239-242
The enzyme inulinase (2,1-β-d-fructan fructanohydrolase, EC 3.2.1.7), prepared from Kluyveromyces marxianus has been immobilized using an inorganic solid support, molecular sieve 4A via the metal link method. The immobilized enzyme had around 22 units of inulinase activity per g of the support with retention of 72% of the original activity. The optimum protein to molecular sieve ratio for the maximum retention of inulinase activity was 9 mg/g molecular sieve. The properties of soluble and immobilized enzyme differed in many respects. The optimum pH of the enzyme shifted from 6 to 5 and the optimum temperature of enzyme activity changed from 50 to 55°C. Km values were 6.7 mM for soluble enzyme and 10 mM for immobilized enzyme. The heat stability of the enzyme was improved by immobilization. Immobilized enzyme retained about 76% of the original activity after 40 days of storage at room temperature (30±2°C). 相似文献
18.
Kluyveromyces marxianus cells with inulinase (2,1-β-d-fructan fructanohydrolase, EC 3.2.1.7) activity have been immobilized in open pore gelatin pellets with retention of > 90% of the original activity. The open pore gelatin pellets with entrapped yeast cells were obtained by selective leaching out of calcium alginate from the composite matrix, followed by crosslinking with glutaraldehyde. Enzymatic properties of the gelatin-entrapped cells were studied and compared with those of the free cells. The immobilization procedure did not alter the optimum pH of the enzymatic preparation; the optimum for both free and immobilized cells was pH 6.0. The optimum temperature of inulin hydrolysis was 10°C higher for immobilized cells. Activation energies for the reaction with the free and immobilized cells were calculated to be 6.35 and 2.26 kcal mol?1, respectively. Km values were 8 mM inulin for the free cells and 9.52 mM for the immobilized cells. The thermal stability of the enzyme was improved by immobilization. Free and immobilized cells showed fairly stable activities between pH 4 and 7, but free cell inulinase was more labile at pH values below 4 and above 7 compared to the immobilized form. There was no loss of enzyme activity of the immobilized cells on storage at 4°C for 30 days. Over the same period at room temperature only 6% of the original activity was lost. 相似文献
19.
《Biocatalysis and Biotransformation》2013,31(2-3):71-76
AbstractMethods of cellulase immobilization on magnetic particles via glutaraldehyde binding were studied. The binding was confirmed by transmission electronic microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and vibrating sample magnetometry (VSM). Samples analyzed by TEM and XRD showed that the magnetic particles with or without bound cellulase were all nanosized particles with a mean diameter of 11.5 nm, and the binding process did not cause significant changes in particle size and structure. Analysis by FTIR showed that the binding of cellulase to the magnetic nanoparticles might be via covalent bonding between residual amine groups on Fe3O4 nanoparticles and amine groups of the cellulase. The VSM analysis showed that magnetic nanoparticles with or without bound cellulase were all superparamagnetic. The immobilized cellulase had a wider pH and temperature range and improved storage stability compared with the free enzyme. Determination of the Michaelis constants revealed that the immobilized cellulase had a greater affinity for the cellulosic substrate than the free enzyme. The immobilized cellulase showed better performance on hydrolysis of steam-exploded corn stalks than of bleached sulfite bagasse pulp. 相似文献
20.
G��lay Bayramo?lu Beg��m Alt?nta? M. Yakup Ar?ca 《Bioprocess and biosystems engineering》2011,34(2):127-134
Polyacrylonitrile film (PAN) surfaces were modified with chemical polymerization of conductive polyaniline (PANI) in the presence
of potassium dichromate as an oxidizing agent. The conductive films were used for immobilization of uricase. The surface resistance
of the conductive film in this work was found to be 0.97 kΩ/cm. The maximum amount of immobilized enzyme on conductive film
containing 2.4% PANI was about 216 μg/cm2. The optimum pH for free and immobilized enzymes was observed at 7.0 and 7.5, respectively. The K
m values for free and immobilized uricase were found to be 94 and 138 μM, respectively. V
max values were calculated as 1.87 and 1.63 U/mg protein for the free and immobilized enzymes, respectively. Immobilized uricase
exhibited ~68% of its original activity even after 2 months of storage at 4 °C while the free enzyme lost its initial activity
within 4 weeks. 相似文献