Stączek Sylwia, Grygorczuk Katarzyna, Zdybicka-Barabas Agnieszka, Siemińska-Kuczer Anna, Vertyporokh Lidiia, Andrejko Mariola, Wojda Iwona, Cytryńska Małgorzata
Department of Immunobiology, Institute of Biology and Biochemistry, Faculty of Biology and Biotechnology, Maria Curie-Skłodowska University, 19 Akademicka St., 20-033 Lublin, Poland.
Postepy Biochem. 2017;63(4):315-325.
Phenoloxidases are oxidoreducting enzymes whose main function is the oxidation of phenols. The term phenoloxidase is often used interchangeably to describe three different enzymes: tyrosinase (EC 1.14.18.1), catechol oxidase, and laccase. Of these, only tyrosinase has two activities: (1) oxygenase activity to hydroxylate monophenols to ortho-diphenols and (2) oxidase activity responsible for further oxidation of ortho-diphenols to ortho-quinones. Tyrosinase is a key enzyme involved in the melanogenesis process, resulting in the formation of black-brown eumelanin and yellow-red feomelanin. In addition to the pigmentary role, human melanin protects against harmful ultraviolet radiation, while in invertebrate animals melanin is involved in the process of cuticle hardening, wound healing, clot formation, maintenance of intestinal homeostasis and defense reactions. In invertebrates, the tyrosinase is synthesized as a proenzyme that is activated by a serine proteases' cascade known as the phenoloxidase system. This system is considered as one of the innate immunity mechanisms.
酚氧化酶是一类氧化还原酶，其主要功能是氧化酚类物质。酚氧化酶这个术语常被交替使用来描述三种不同的酶：酪氨酸酶（EC 1.14.18.1）、儿茶酚氧化酶和漆酶。其中，只有酪氨酸酶具有两种活性：（1）将单酚羟基化为邻二酚的加氧酶活性，以及（2）将邻二酚进一步氧化为邻醌的氧化酶活性。酪氨酸酶是黑色素生成过程中的关键酶，导致黑褐色真黑素和黄红色褐黑素的形成。除了色素作用外，人类黑色素可抵御有害的紫外线辐射，而在无脊椎动物中，黑色素参与角质层硬化、伤口愈合、凝血形成、肠道内环境稳定维持和防御反应等过程。在无脊椎动物中，酪氨酸酶以前体酶的形式合成，该前体酶由一种称为酚氧化酶系统的丝氨酸蛋白酶级联反应激活。这个系统被认为是先天免疫机制之一。
