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| The kinetic parameters of partially purified phenoloxidase (PO, EC. 1.14.18.1) from the larvae of Anomala corpulenta M. were determined, using L-3, 4-dihydroxyphenylalanine (L-DOPA) as substrate. The optimal pH and temperature of the enzyme for the oxidation of L-DOPA were determined to be at pH 7.5 and at 50 C, respectively. At pH 7.5 and 50 C, the Michaelis constant (Km) and maximal velocity (Vm) of the enzyme for the oxidation of L-DOPA were determined to be 11.11 mmol/L and 107.53 U/mg, respectively, and the Km and Vm of PO for the oxidation of catechol were 9.52 mmol/L and 41.67 U/mg, respectively. Morin could effectively inhibit the activity of phenoloxidase and this inhibition was reversible and competitive, with the IC50 of 1.05 mmol/L. The inhibition constants were estimated to be 0.54 mmol/L. |
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| Keywords:Anomala corpulenta, Phenoloxidase, Morin, inhibitory mechanism |
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