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Catalytic activity of versatile peroxidase from Bjerkandera fumosa in aqueous solutions of water–miscible organic solvents

Paper ID Volume ID Publish Year Pages File Format Full-Text
44299 46014 2006 6 PDF Available
Title
Catalytic activity of versatile peroxidase from Bjerkandera fumosa in aqueous solutions of water–miscible organic solvents
Abstract

Versatile peroxidase (VP) from the white rot fungus Bjerkandera fumosa was isolated and purified by ion exchange and gel filtration chromatography. Its primary catalytic activity in oxidation of Mn(II) was studied in aqueous solutions in the presence of varying concentrations (up to 8 M) of acetonitrile (MeCN), dimethylsulfoxide (DMSO), ethanol, and n-propanol. The observed maximum reaction rate values decreased with the addition of organic solvents in the order: MeCN < n-propanol < DMSO < ethanol. The observed Michaelis constant values decreased in the order: DMSO < MeCN < n-propanol. This lead to various shapes of the specific activity constant values (ks = Vmax/KM) of VP in oxidation of Mn(II) in solutions of different organic solvents. KM values of typical organic substrates of enzymatic reactions increase with addition of organic solvents, due to unfavorable partitioning of substrates between the medium and the active center of the enzyme. In case of inorganic ions, the decrease of the medium polarity caused by addition of the organic solvent should lead to the enhancement of substrate binding by the enzyme due to the variation in the activity coefficient/solubility of the substrates in the studied systems, and therefore to the decrease of KM values. The results of our experiments confirm this expectation. To further support this thesis, the effect of ethanol on oxidation of 2,6-dimethoxyphenol catalyzed by VP in the presence of Mn(II) was also studied. The observed Vmax values were exponentially decreasing with the solvent concentration, while the KM versus ethanol concentration curve passed through a minimum. The later effect could be described by two exponential relationships (the one decreasing for Mn(II) and the other one increasing for 2,6-dimethoxyphenol).

Keywords
Versatile peroxidase; Organic solvent; Denaturation; Inorganic and organic substrate
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Catalytic activity of versatile peroxidase from Bjerkandera fumosa in aqueous solutions of water–miscible organic solvents
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 308, 10 July 2006, Pages 56–61
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
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Price was $35.95
You save - $31
Price after discount Only $4.95
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