Urease immobilized on nylon: preparation and properties

Anita, A.; Sastry, C. S. P.; Hashim, Mohd Ali

doi:10.1007/s004490050381

Cited by 9 publications

(2 citation statements)

References 23 publications

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“…Besides its use in agricultural effluent treatment, immobilized urease has found applications in blood detoxification and urea removal from beverages and food (). The broad range of applications of this enzyme promoted intensive work on the preparation and characterization of urease derivatives ( − ). The use of immobilized enzymes greatly reduces the expense of any biotechnological process requiring enzymes.…”

Section: Introductionmentioning

confidence: 99%

Advantages of Using Non-isothermal Bioreactors in Agricultural Waste Water Treatment by Means of Immobilized Urease. Study on the Influence of Spacer Length and Immobilization Method

Sherif

Martino

Travascio

et al. 2002

J. Agric. Food Chem.

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The behavior of three different catalytic membranes, obtained by immobilizing urease on nylon sheets chemically grafted with methyl methacrylate, was studied in a bioreactor operating under isothermal and non-isothermal conditions. Membrane activation was carried out by condensation or acyl azide reaction, and spacers of different lengths, such as hexamethylendiamine or hydrazine, were used. Under isothermal conditions, the activities of the catalytic membranes and soluble urease were characterized as a function of pH, temperature, and urea concentration. Both enzyme forms showed the same optimum pH, whereas the optimum temperature was lower for the immobilized enzymes. The spacer length appeared to determine broader pH- and temperature-activity profiles for the urease derivatives. The apparent K(m) values of the insoluble urease were dependent on membrane type and were higher than those of the soluble counterpart, thus indicating an affinity loss for urea. Under non-isothermal conditions, all membranes exhibited an increase of percentage activity proportional to the applied temperature difference and decreasing with the increase of urea concentrations. A decrease of the apparent K(m) was also observed. These results suggest that substrate diffusion limitations due to the immobilization process can be overcome in the presence of temperature gradients. In addition, the remarkable reduction of the production times supports the use of non-isothermal bioreactors for the treatment of urea-polluted waste waters.

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Section: Introductionmentioning

confidence: 99%

Advantages of Using Non-isothermal Bioreactors in Agricultural Waste Water Treatment by Means of Immobilized Urease. Study on the Influence of Spacer Length and Immobilization Method

Sherif

Martino

Travascio

et al. 2002

J. Agric. Food Chem.

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“…Enhanced thermal activity has been reported for several covalently bound ureases, e.g. nylon‐ and vermiculite‐immobilized jack‐bean urease showed highest relative activity at 65 °C compared with free urease at 25 °C; chitosan‐immobilized pigeonpea urease showed maximum activity at 77 °C compared with free enzyme at 47 °C whereas jack bean urease immobilized on sieve 4A showed maximum activity at 65 °C [6,14,17,18].…”

Section: Resultsmentioning

confidence: 99%

Immobilization of pigeonpea (Cajanus cajan) urease on DEAE‐cellulose paper strips for urea estimation

Reddy

Srivastava

Dey

et al. 2004

Biotech and App Biochem

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Pigeonpea ( Cajanus cajan ) urease was immobilized on 1 cmx1 cm DEAE-cellulose paper strips. The optimum immobilization (51% activity) was observed at 4 degrees C, with a protein concentration of 1.0 mg/strip. The apparent optimum pH shifted from 7.3 to 6.8. Immobilized urease showed an optimal stability temperature of 67 degrees C, compared with 47 degrees C for the soluble urease. Time-dependent kinetics of the thermal inactivation of the immobilized urease were examined and found to be monophasic as compared with the soluble enzyme, which was biphasic. The Michaelis constant ( K (m)) for the DEAE-cellulose-immobilized urease was found to be 4.75 mM, 1.5 times higher than the soluble enzyme. Immobilized strips stored at 4 degrees C showed an increased half-life ( t (1/2)=150 days). There was practically no leaching of the enzyme from the immobilized strips over a period of 2 weeks. These strips were used for estimating the urea content of blood samples; the results obtained matched well with those obtained in a clinical laboratory through an Autoanalyzer(R) (Zydus Co., Rome, Italy). The easy availability of pigeonpea urease, the ease of its immobilization on DEAE-cellulose strips and the significantly lower cost of urease described in the present study makes it a suitable product for future applications in diagnostics.

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Preparation and characterization of urease immobilized onto porous chitosan beads for urea hydrolysis

Chen

Chiu

1999

Bioprocess Engineering

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Urease was covalently immobilized onto porous chitosan beads via primary amine groups connected to the backbone via a six-carbon linear alkyl spacer. The optimum conditions for enzyme immobilization are activating the beads with 1%(w/w) glutaraldehyde, reacting the activated beads in pH 7 buffer with the enzyme, using an enzyme to bead weight ratio of 25, and without lyophilization. Chitosan-bound urease was found to fully retain its speci®c activity. Properties of the immobilized urease were characterized under batch and¯ow conditions. Increased optimum reaction temperature, enhanced thermal stability and storage stability, and excellent reusability were found after enzyme immobilization. Continuous hydrolysis of urea solution was studied in a column packed with the enzyme-containing beads for its possible application in regenerating dialysate solution during hemodialysis.

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Urease immobilized on nylon: preparation and properties

Cited by 9 publications

References 23 publications

Advantages of Using Non-isothermal Bioreactors in Agricultural Waste Water Treatment by Means of Immobilized Urease. Study on the Influence of Spacer Length and Immobilization Method

Advantages of Using Non-isothermal Bioreactors in Agricultural Waste Water Treatment by Means of Immobilized Urease. Study on the Influence of Spacer Length and Immobilization Method

Immobilization of pigeonpea (Cajanus cajan) urease on DEAE‐cellulose paper strips for urea estimation

Preparation and characterization of urease immobilized onto porous chitosan beads for urea hydrolysis

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