Armstrong P B, Armstrong M T, Quigley J P
Department of Zoology, University of California, Davis 95616-8755.
Mol Immunol. 1993 Jul;30(10):929-34. doi: 10.1016/0161-5890(93)90017-6.
Homologues of two plasma proteins of vertebrates, alpha 2-macroglobulin and C-reactive protein, participate in a hemolytic system of the ancient arthropod, Limulus polyphemus. C-reactive protein, which can under the appropriate circumstances activate the classical pathway of the mammalian complement system, is an essential element of the hemolytic system of Limulus. The selective removal of C-reactive protein from the plasma with phosphorylethanolamine-agarose inactivated hemolysis. Addition of affinity-purified C-reactive protein to inactive plasma restored activity. Exposure of plasma to phosphorylethanolamine in solution potentiated hemolysis. alpha 2-Macroglobulin is a member of the same protein family as the complement protein C3 and both require an intact thiol ester for activity. Treatment of Limulus plasma with methylamine under conditions that inactivate thiol-ester-containing proteins reduced the hemolytic activity of some plasma preparations. Addition of purified Limulus alpha 2-macroglobulin to the methylamine-treated plasma restored hemolytic activity. However, alpha 2-macroglobulin is not necessary for hemolysis since the hemolytic activity of some pooled plasma preparations was insensitive to methylamine treatment under conditions that inactivated alpha 2-macroglobulin. Purified C-reactive protein was hemolytic in the absence of alpha 2-macroglobulin. These observations suggest that the proteins in Limulus plasma that participate in hemolysis represent the components of an ancient invertebrate defense system with distant evolutionarily affinities to the vertebrate complement system.
脊椎动物的两种血浆蛋白α2-巨球蛋白和C反应蛋白的同源物，参与了古老节肢动物美洲鲎的溶血系统。C反应蛋白在适当情况下可激活哺乳动物补体系统的经典途径，是美洲鲎溶血系统的一个重要元素。用磷酸乙醇胺-琼脂糖从血浆中选择性去除C反应蛋白会使溶血失活。向失活的血浆中添加亲和纯化的C反应蛋白可恢复活性。使血浆暴露于溶液中的磷酸乙醇胺会增强溶血作用。α2-巨球蛋白与补体蛋白C3属于同一蛋白家族，两者的活性都需要完整的硫酯。在使含硫酯的蛋白失活的条件下用甲胺处理美洲鲎血浆，会降低某些血浆制剂的溶血活性。向经甲胺处理的血浆中添加纯化的美洲鲎α2-巨球蛋白可恢复溶血活性。然而，α2-巨球蛋白对于溶血并非必需，因为在使α2-巨球蛋白失活的条件下，一些混合血浆制剂的溶血活性对甲胺处理不敏感。纯化的C反应蛋白在没有α2-巨球蛋白的情况下具有溶血作用。这些观察结果表明，美洲鲎血浆中参与溶血的蛋白代表了一种古老的无脊椎动物防御系统的组成部分，与脊椎动物补体系统在进化上有遥远的亲缘关系。
