Physical and chemical properties of human plasma alpha2-macroglobulin.
Physical and chemical properties of human plasma alpha2-macroglobulin.
复制标题
人血浆 α2-巨球蛋白的物理和化学特性。
作者：
P. Hall;R. Roberts
用两种不同的方法从人血浆中纯化α 2-m （α 2-巨球蛋白）。通过检测蛋白质制剂均匀性的通常标准，这些alpha2M制剂没有可检测到的杂质，并且通过十二烷基硫酸钠/聚丙烯酰胺凝胶电泳显示，在尿素还原后，这些alpha2M制剂的单组分为185000道尔顿。用重量测定的-v = 0.731 ml/g进行沉淀平衡实验，发现alpha2M的分子量为718000。利用一种新型的不连续聚丙烯酰胺-凝胶体系研究了几种蛋白酶与alpha2M的相互作用，该体系显示了酶络合的alpha2M与游离的alpha2M的明显分离。这些研究表明尿激酶以及胰蛋白酶、凝乳胰蛋白酶、纤溶酶和凝血酶与α - ham形成复合物。在尿素中还原alpha2M-胰蛋白酶复合物后，十二烷基硫酸钠/聚丙烯酰胺凝胶电泳证实了胰蛋白酶与alpha2M相互作用时，185000道尔顿亚基分裂为85000道尔顿亚基。测定了alpha2M的氨基酸组成、碳水化合物含量、280 nm处的吸收系数、比折光增量和沉淀系数。研究了不同贮藏条件下alpha2M制剂胰蛋白酶结合活性的稳定性。
Alpha2-M (alpha2-macroglobulin) was purified from human plasma by two different procedures. As well as having no detectable impurities by the usual criteria for testing the homogeneity of protein preparations, these alpha2M preparations showed a single component, after reduction in urea, of 185000 daltons by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. The molecular weight of the alpha2M was found to be 718000 by sedimentation equilibrium experiments using the gravimetrically determined -v of 0.731 ml/g. The interaction of several proteinases with alpha2M was studied by using a novel discontinuous polyacrylamide-gel system, which showed clear separation of the enzyme-complexed alpha2M from the free alpha2M. These studies indicated that urokinase, as well as trypsin, chymotrypsin, plasmin and thrombin forms complexes with alphaM. The cleavage of the 185000-dalton subunit to a 85000-dalton species on interaction of trypsin with alpha2M was demonstrated by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis after reduction of the alpha2M-trypsin complex in urea. The amino acid composition, carbohydrate content, absorption coefficient at 280 nm, the specific refractive increment and the sedimentation coefficient for these alpha2M preparations were measured. The stability of the trypsin-binding activity of the alpha2M preparations was also studied under several storage situations.