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Thermal Characterization of Purified Glucose Oxidase from A Newly Isolated Aspergillus Niger UAF-1.

Anjum Zia M - J Clin Biochem Nutr (2007)

Bottom Line: Temperature optimum for glucose oxidase, catalyzed D-glucose oxidation was 40 degrees C.The enzyme showed a high thermostability having a half-life 30 min, enthalpy of denaturation 99.66 kJ mol(-1) and free energy of denaturation 103.63 kJ mol(-1).These characteristics suggest the use of glucose oxidase from Aspergillus niger UAF-1 as an analytical reagent and in the design of biosensors for clinical, biochemical and diagnostic assays.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry (Biochemistry), University of Agriculture, Faisalabad, Pakistan.

ABSTRACT
An intracellular glucose oxidase was isolated from the mycelium extract of a locally isolated strain of Aspergillus niger UAF-1. The enzyme was purified to a yield of 28.43% and specific activity of 135 U mg(-1) through ammonium sulfate precipitation, anion exchange and gel filtration chromatography. The enzyme showed high affinity for D-glucose with a Km value of 2.56 mM. The enzyme exhibited optimum catalytic activity at pH 5.5. Temperature optimum for glucose oxidase, catalyzed D-glucose oxidation was 40 degrees C. The enzyme showed a high thermostability having a half-life 30 min, enthalpy of denaturation 99.66 kJ mol(-1) and free energy of denaturation 103.63 kJ mol(-1). These characteristics suggest the use of glucose oxidase from Aspergillus niger UAF-1 as an analytical reagent and in the design of biosensors for clinical, biochemical and diagnostic assays.

No MeSH data available.


Related in: MedlinePlus

Double reciprocal plot to determine the kinetic constants for D-glucose
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Figure 4: Double reciprocal plot to determine the kinetic constants for D-glucose

Mentions: Kinetic and thermodynamic parameters for irreversible thermal denaturation of glucose oxidase were determined by incubating the enzyme in 50 mM MES monohydrate buffer (pH 5.5) at a particular temperature. Aliquots were withdrawn at different times, cooled on ice for 3 h [18] and assayed for enzyme activity at 25°C. This procedure was repeated at five different temperatures ranging from 45 to 60°C. The data were fitted to first order plots (Fig. 4) and analyzed as described earlier [19]. The thermodynamic parameters for thermostability were calculated by rearranging the Eyring’s absolute rate equation derived from the transition state theory as described by Siddiqui et al. [20].


Thermal Characterization of Purified Glucose Oxidase from A Newly Isolated Aspergillus Niger UAF-1.

Anjum Zia M - J Clin Biochem Nutr (2007)

Double reciprocal plot to determine the kinetic constants for D-glucose
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2170954&req=5

Figure 4: Double reciprocal plot to determine the kinetic constants for D-glucose
Mentions: Kinetic and thermodynamic parameters for irreversible thermal denaturation of glucose oxidase were determined by incubating the enzyme in 50 mM MES monohydrate buffer (pH 5.5) at a particular temperature. Aliquots were withdrawn at different times, cooled on ice for 3 h [18] and assayed for enzyme activity at 25°C. This procedure was repeated at five different temperatures ranging from 45 to 60°C. The data were fitted to first order plots (Fig. 4) and analyzed as described earlier [19]. The thermodynamic parameters for thermostability were calculated by rearranging the Eyring’s absolute rate equation derived from the transition state theory as described by Siddiqui et al. [20].

Bottom Line: Temperature optimum for glucose oxidase, catalyzed D-glucose oxidation was 40 degrees C.The enzyme showed a high thermostability having a half-life 30 min, enthalpy of denaturation 99.66 kJ mol(-1) and free energy of denaturation 103.63 kJ mol(-1).These characteristics suggest the use of glucose oxidase from Aspergillus niger UAF-1 as an analytical reagent and in the design of biosensors for clinical, biochemical and diagnostic assays.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry (Biochemistry), University of Agriculture, Faisalabad, Pakistan.

ABSTRACT
An intracellular glucose oxidase was isolated from the mycelium extract of a locally isolated strain of Aspergillus niger UAF-1. The enzyme was purified to a yield of 28.43% and specific activity of 135 U mg(-1) through ammonium sulfate precipitation, anion exchange and gel filtration chromatography. The enzyme showed high affinity for D-glucose with a Km value of 2.56 mM. The enzyme exhibited optimum catalytic activity at pH 5.5. Temperature optimum for glucose oxidase, catalyzed D-glucose oxidation was 40 degrees C. The enzyme showed a high thermostability having a half-life 30 min, enthalpy of denaturation 99.66 kJ mol(-1) and free energy of denaturation 103.63 kJ mol(-1). These characteristics suggest the use of glucose oxidase from Aspergillus niger UAF-1 as an analytical reagent and in the design of biosensors for clinical, biochemical and diagnostic assays.

No MeSH data available.


Related in: MedlinePlus