Phenoloxidase an important constituent in crustacean immune system-A review

Abstract

In crustaceans, the circulating hemocytes play the most important role in the protection of the animal against invading pathogens. Therefore, hematopoiesis is essential to produce new hemocytes which can particpate in the cellular defences. Crustacean hemocytes posses phenoloxidases whichcatalyze the melanization and sclerotization of the new postmolt exoskeleton, and involved in the immune response. Hemocyanin, phylogenetically related to phenoloxidase, can function as a phenoloxidase under certain conditions. Both of them convert diphenols to o-quinones, but only the hemocyte phenoloxidase are able to catalyze the conversion of monophenols to diphenols. This review demonstrates the synthesis and mechanism of phenoloxidase in the innate immune response of crustacean. In addition, the purification and expression level of phenoloxidase cascade in crustacean is elucidated.在甲殼類，循環血淋巴球抵抗病原扮演重要角色，因此，血球增生組織持續增生血淋巴球，作為細胞免疫防禦。甲殼類血淋巴球細胞帶有酚氧化酵素，可催化黑色素反應、脫殼後殼的硬化，以及免疫反應。在某些情形下，血藍素在系統發育上與酚氧化酵素相似，血藍素與酚氧化酵素均具有酚氧化酵素的功能。血藍素與酚氧化酵素兩者都能將雙酚(diphenols)轉為鄰醌(o-quinones)，但只有血淋巴球的酚氧化酵素可將單酚(monophenols)催化為雙酚。本篇回顧同時闡明甲殼類先天性免疫反應中酚氧化酵素流程蛋白的純化與表現。