Enzymatic properties of phenoloxidase from Pieris rapae (Lepidoptera) larvae

• 来源期刊: 中国昆虫科学（英文版）
• 关键词: inhibitory mechanism Pieris rapae phenoloxidase properties 4- hexylresorcinol 4-dodecylresorcinol
• 年，卷（期）: 2006,（4）
• 页码范围: 251-256
• 页数: 6页
• 语种: 英文

摘要

The kinetic parameters of partially purified phenoloxidase (PO, EC. 1.14.18.1) from the 5th instar larvae of Pieris rapae (Lepidoptera) 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 7.0 and at 42℃,respectively. The enzyme was stable between pH 6.5 and 7.4 and at temperatures lower than 37℃. At pH 6.8 and 37℃, the Michaelis constant (Km) and maximal velocity (Vm) of the enzyme for the oxidation of L-DOPA were determined to be 0.80 mmol/L and 1.84 μmol/ L/min, respectively. Tetra-hexylresorcinol and 4-dodecylresorcinol effectively inhibited activity of phenoloxidase and this inhibition was reversible and competitive, with the IC50 of 1.50 and 1.12μmol/L, respectively. The inhibition constants were estimated to be 0.50 and 0.47μmol/L, respectively.