Slifman N R, Loegering D A, McKean D J, Gleich G J
J Immunol. 1986 Nov 1;137(9):2913-7.
The eosinophil granule contains a series of basic proteins, including major basic protein, eosinophil peroxidase, eosinophil-derived neurotoxin (EDN), and eosinophil cationic protein (ECP). Both EDN and ECP are neurotoxins and helminthotoxins. Comparison of the partial N-terminal amino acid sequences of EDN and ECP showed 67% identity; surprisingly, they also showed structural homology to pancreatic ribonuclease (RNase). Therefore, we determined whether EDN and ECP possess RNase enzymatic activity. By spectrophotometric assay of acid soluble nucleotides formed from yeast RNA, purified EDN showed RNase activity similar to bovine pancreatic RNase, whereas ECP was 50 to 100 times less active. The RNase activity associated with ECP was not significantly inhibited after exposure of ECP to polyclonal or monoclonal antibody to EDN. These results indicate that EDN and ECP both possess RNase activity, the RNase activity of EDN and ECP is specific, and EDN and ECP have maintained not only structural but also functional homology to pancreatic RNase.
嗜酸性粒细胞颗粒包含一系列碱性蛋白，包括主要碱性蛋白、嗜酸性粒细胞过氧化物酶、嗜酸性粒细胞衍生神经毒素（EDN）和嗜酸性粒细胞阳离子蛋白（ECP）。EDN和ECP均为神经毒素和蠕虫毒素。对EDN和ECP的部分N端氨基酸序列进行比较，发现二者具有67%的同源性；令人惊讶的是，它们还与胰腺核糖核酸酶（RNase）存在结构同源性。因此，我们测定了EDN和ECP是否具有RNase酶活性。通过分光光度法检测由酵母RNA形成的酸溶性核苷酸，纯化后的EDN显示出与牛胰腺RNase相似的RNase活性，而ECP的活性则低50至100倍。将ECP与EDN的多克隆或单克隆抗体孵育后，与ECP相关的RNase活性并未受到显著抑制。这些结果表明，EDN和ECP均具有RNase活性，EDN和ECP的RNase活性具有特异性，并且EDN和ECP不仅与胰腺RNase保持结构同源性，还保持功能同源性。
