Hergenhahn H G, Hall M, Söderhäll K
Institut fur Zoophysiologie, Rheinische Friedrich-Wilhelms-Universität, Bonn, FRG.
Biochem J. 1988 Nov 1;255(3):801-6. doi: 10.1042/bj2550801.
An alpha 2-macroglobulin (alpha 2M)-like proteinase inhibitor from plasma of the crayfish Pacifastacus leniusculus was purified to apparent homogeneity by acid precipitation, hydrophobic interaction chromatography, affinity chromatography on concanavalin A-Sepharose and anion-exchange chromatography. The subunit Mr is about 190,000. Pore-size-limit electrophoresis proved the native protein to be a dimer. The purified protein resembled vertebrate alpha 2 Ms in that it protected trypsin from inhibition by soyabean trypsin inhibitor, and in its sensitivity to methylamine treatment. Methylamine also prevented the protein from being autolytically cleaved into Mr 60,000 and 140,000 fragments when subjected to heat treatment. The amino acid composition showed similarities with both human alpha 2 M and an alpha 2 M-like protein from the arthropod Limulus polyphemus. These data indicate that this Pacifastacus alpha 2M-like protein (P alpha 2M) may be a distantly related homologue of vertebrate alpha 2Ms.
通过酸沉淀、疏水相互作用色谱、伴刀豆球蛋白A-琼脂糖亲和色谱和阴离子交换色谱，从美洲螯龙虾血浆中纯化出一种α2-巨球蛋白（α2M）样蛋白酶抑制剂，达到了表观均一性。亚基的相对分子质量约为190,000。孔径极限电泳证明天然蛋白是二聚体。纯化后的蛋白与脊椎动物α2M相似，它能保护胰蛋白酶不被大豆胰蛋白酶抑制剂抑制，并且对甲胺处理敏感。甲胺还能防止该蛋白在热处理时自溶裂解成相对分子质量为60,000和140,000的片段。氨基酸组成显示其与人类α2M以及节肢动物鲎的一种α2M样蛋白都有相似之处。这些数据表明这种美洲螯龙虾α2M样蛋白（Pα2M）可能是脊椎动物α2M的远亲同源物。
