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Title: Kinetics in microemulsion V. Glucose oxidase catalyzed oxidation of β-D-glucose in aqueous, micellar and water-in-oil microemulsion media
Authors: Gupta, Syamasri
Mukhopadhyay, Lana
Moulik, S P
Keywords: microemulsion;enzyme activity;inhibitor;anisotropy
Issue Date: Oct-2003
Publisher: CSIR
Abstract: The oxidation of β-D-glucose by the enzyme glucose oxidase was studied in aqueous medium, in solutions of surfac-tants AOT (2-ethylhexylsulfosuccinate, sodium salt) TX-100 (polyethylene glycol p-tert octyl phenyl ether) and in w/o mi-croemulsion medium (water/AOT/decane) at different water/AOT mole ratio (ω), pH, temperature and in presence of addi-tives. The time-dependent activities of the enzyme in aqueous and microemulsion media were determined. The catalytic process was retarded in the presence of TX-100 and AOT. In microemulsion medium, kcat values exhibited a deformed W-shaped profile with ω. At pH 7, a maximum value of kcat was observed at ω = 10.6. The kcat values were found to be higher in microemulsion medium than in aqueous medium at both pH’s 7 and 8. Activation parameters for the kinetic process were evaluated together with the thermodynamics of the enzyme-substrate Michaelis complex. The ΔG* was lower, whereas ΔH* and ΔS* were higher in microemulsion than in water. The Michaelis constant, KM was also lower in microemulsion. The in-hibition effects of the additives, NaNO3 and NaC were studied in both aqueous and microemulsion media by examining their influences on catalytic constant, kcat and Michaelis constant KM. In microemulsion, both the additives NaNO3 and NaC produced non-competitive inhibition.
Page(s): 340-349
ISSN: 0301-1208
Appears in Collections:IJBB Vol.40(5) [October 2003]

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