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KMID : 1094720100150060993
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Biotechnology and Bioprocess Engineering
2010 Volume.15 No. 6 p.993 ~ p.997
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Substrate stabilization and noncompetitive inhibition effects of a water-miscible ionic liquid [BMPy][BF4] in the catalysis of horseradish peroxidase
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Park Jung-Hee
Kwon O.-Yul
Ryu Keun-Garp
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Abstract
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The inhibition mechanism of a water-miscible ionic liquid, N-butyl-3-methypyridinium tetrafluoroborate ([BMPy][BF4]), on the catalysis of horseradish peroxidase (HRP) was investigated. The K m value for the oxidation of guaiacol (2-methoxyphenol) with H2O2 catalyzed by HRP increased from 2.8 mM in 100% water to 12.6 mM in 25% (v/v) [BMPy][BF4]. This increase of K m by the ionic liquid was elucidated to be caused by the strong stabilization of the ground state of guaiacol by the ionic liquid. On the contrary, the k cat value for the HRP-catalyzed reaction decreased from 13.8/sec in 100% water to 6.7/sec in 25% (v/v) [BMPy][BF4]. Such decrease of k cat value of HRP catalysis by the increasing content of [BMPy][BF4] was described using the noncompetitive inhibition of the enzyme by the ionic liquid. The value of the inhibition constant of [BMPy][BF4] was 1.48 M indicating that the ionic liquid exerts a weak noncompetitive inhibition effect on the HRP catalysis.
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KEYWORD
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anion, horseradish peroxidase, ionic liquid, noncompetitive inhibition, thermodynamics
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