We characterized the optimal conditions for measuring serum phenoloxidase activity and its functional activity and susceptibility to an inhibitor and various activators in an anomuran crab, Albunea symmysta (Linnaeus, 1758). The substrate affinity of the phenoloxidase (PO) enzyme was determined using different phenolic substrates in which only diphenols were found to be oxidized. The enzyme was characterized as a catecholoxidase-type of PO and 3,4-dihydroxy-DL-phenylalanine (DL-Dopa), the enzyme showing the highest substrate affinity to the serum. The optimal enzyme activity was observed at 5 mM DL-Dopa in 10 mM Tris-HCl buffer at a pH of 7.5 at 25 °C for 10 min, and absorbance at 470 nm. Serum-PO activity was inhibited by 7 mM phenylthiourea (PTU), and activated by activators such as trypsin, chymotrypsin, pronase-E, and detergent-like sodium dodecyl sulfate (SDS). We also identified the chemicals causing in vitro inhibition or activation of the enzyme as a serum of the crab having a potent PO activity.

中文翻译：

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anomura 蟹血淋巴中的血清酚氧化酶活性 Albunea symmysta (Linnaeus, 1758) (十足目: Anomura: Albuneidae)

我们描述了测量血清酚氧化酶活性及其功能活性以及对 anmuran 蟹 Albunea symmysta (Linnaeus, 1758) 中的抑制剂和各种激活剂的敏感性的最佳条件。酚氧化酶 (PO) 酶的底物亲和力是使用不同的酚底物测定的，其中发现只有二酚被氧化。该酶被表征为 PO 和 3,4-二羟基-DL-苯丙氨酸 (DL-Dopa) 的儿茶酚氧化酶类型，该酶对血清显示出最高的底物亲和力。在 5 mM DL-Dopa 在 10 mM Tris-HCl 缓冲液中观察到最佳酶活性，pH 为 7.5，25 °C 下 10 分钟，吸光度在 470 nm。血清-PO 活性被 7 mM 苯硫脲 (PTU) 抑制，并被胰蛋白酶、胰凝乳蛋白酶、链霉蛋白酶 E、和类似洗涤剂的十二烷基硫酸钠 (SDS)。我们还鉴定了引起体外抑制或激活酶的化学物质作为具有强 PO 活性的螃蟹血清。