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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

Irreversible thermal inactivation of Aspergillus niger UAF-1 glucose oxidase. [Closed triangle (45°C), Open (48°C), Closed circle (52°C), Open circle (56°C) and Open square (60°C)].
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Figure 5: Irreversible thermal inactivation of Aspergillus niger UAF-1 glucose oxidase. [Closed triangle (45°C), Open (48°C), Closed circle (52°C), Open circle (56°C) and Open square (60°C)].

Mentions: Glucose oxidase from Aspergillus niger UAF-1 was thermally stable at 45°C with half-life of 173 minutes. However at 60°C it was less stable and displayed a half-life of 30 min under similar conditions (Fig. 5). The enzyme had a range of 99.79–99.66 kJ mol−1 enthalpy of denaturation (ΔH*) at 45°C–60°C. The value of free energy of thermal denaturation (ΔG*) for glucose oxidase was 103.47 kJ mol−1 at 45°C, showing a decreasing trend with increase in temperature. When entropy of inactivation (ΔS*) was calculated at each temperature, it showed negative values. Purified glucose oxidase from Aspergillus niger UAF-1 showed a ΔS* value of –11.92 J mol−1 K−1 at 60°C (Fig. 6, Table 2).


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

Anjum Zia M - J Clin Biochem Nutr (2007)

Irreversible thermal inactivation of Aspergillus niger UAF-1 glucose oxidase. [Closed triangle (45°C), Open (48°C), Closed circle (52°C), Open circle (56°C) and Open square (60°C)].
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 5: Irreversible thermal inactivation of Aspergillus niger UAF-1 glucose oxidase. [Closed triangle (45°C), Open (48°C), Closed circle (52°C), Open circle (56°C) and Open square (60°C)].
Mentions: Glucose oxidase from Aspergillus niger UAF-1 was thermally stable at 45°C with half-life of 173 minutes. However at 60°C it was less stable and displayed a half-life of 30 min under similar conditions (Fig. 5). The enzyme had a range of 99.79–99.66 kJ mol−1 enthalpy of denaturation (ΔH*) at 45°C–60°C. The value of free energy of thermal denaturation (ΔG*) for glucose oxidase was 103.47 kJ mol−1 at 45°C, showing a decreasing trend with increase in temperature. When entropy of inactivation (ΔS*) was calculated at each temperature, it showed negative values. Purified glucose oxidase from Aspergillus niger UAF-1 showed a ΔS* value of –11.92 J mol−1 K−1 at 60°C (Fig. 6, Table 2).

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