Peterson C G, Venge P
Department of Clinical Chemistry, University Hospital, Uppsala, Sweden.
Biochem J. 1987 Aug 1;245(3):781-7. doi: 10.1042/bj2450781.
The interaction between the highly basic and cytotoxic eosinophil cationic protein (ECP) and human plasma proteins is described. The major plasma protein responsible for complex-formation with ECP was shown to be the 'fast' form of alpha 2-macroglobulin (alpha 2M). Large amounts of complexes were observed in a serum obtained from a patient with hypereosinophilic syndrome. The amount of complexes that could be generated in vitro in normal fresh serum was rather low and was even less in fresh citrated plasma. Complex-formation between the non-proteolytic ECP and alpha 2M was augmented in the presence of methylamine. Binding of ECP to alpha 2M was also induced by the proteinases cathepsin G and thrombin, and the binding was competitive with cathepsin G. Methylamine and the proteinases seem to share a common mechanism in inducing binding of ECP. The nature of the ECP-alpha 2M interaction is non-covalent, but withstands high salt concentrations. The interaction with alpha 2M may reflect a mechanism by which the organism protects itself against the deleterious effects of the highly cytotoxic protein ECP.
本文描述了高碱性细胞毒性嗜酸性粒细胞阳离子蛋白（ECP）与人血浆蛋白之间的相互作用。研究表明，与ECP形成复合物的主要血浆蛋白是α2-巨球蛋白（α2M）的“快速”形式。在一名患有嗜酸性粒细胞增多综合征患者的血清中观察到大量复合物。在正常新鲜血清中体外可生成的复合物量相当低，在新鲜枸橼酸盐血浆中则更低。在甲胺存在下，非蛋白水解性的ECP与α2M之间的复合物形成增加。组织蛋白酶G和凝血酶等蛋白酶也可诱导ECP与α2M结合，且该结合与组织蛋白酶G具有竞争性。甲胺和蛋白酶在诱导ECP结合方面似乎具有共同机制。ECP与α2M相互作用的性质是非共价的，但能耐受高盐浓度。与α2M的相互作用可能反映了机体保护自身免受高细胞毒性蛋白ECP有害影响的一种机制。
