engleski

Inhibitory effect of phenylboronic acid on horseradsih peroxidase activity

Abstract: The previous studies investigated the kinetic parameters and inhibition mechanisms of halogenated boroxine dipotassiumtrioxohydroxytetrafluorotriborate (K2[B3O3F4OH]) on enzymes catalase and human carbonic anhydrases. To investigate closely the mechanism of inhibition, it is interesting to test inhibition effect of other boron containing substances on similar enzymes. In this work, the activity of horseradish peroxidase (HRP) was investigated in the presence of phenyilboronic acid of 2, 4 and 6 mM concentration. The HRP activity assay was performed by the measurement of guaiacol peroxidation by H2O2. The initial rate of HRP catalytic reaction to oxidize guaiacol was measured spectrophotometrically by following the increase of absorbance at 470 nm of the reaction mixtures within the first few minutes in absence and in presence of inhibitor. The rate of guaiacol peroxidation decreases in presence of phenylboronic acid. Lineweaver-Burk plots were linear and plotted the family of straight lines intersected in one point on the abscissa indicating non-competitive type inhibition, where the inhibitor and the substrate may both be bound to the enzyme at any given time. Inhibitor reduces the activity of the enzyme and binds equally well to the enzyme whether or not it has already bound the substrate. Inhibition constant was determined using Dixon plot, Ki = 2.36 mM.

Phenylboronic acid horseradish peroxidase inhibition

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