Kingston I B, Kingston B L, Putnam F W
Proc Natl Acad Sci U S A. 1977 Dec;74(12):5377-81. doi: 10.1073/pnas.74.12.5377.
Nine samples of human ceruloplasmin [iron(II):oxygen oxidoreductase; EC 1.16.3.1] prepared by different procedures have been examined for heterogeneity; gel electrophoresis showed that seven contained a number of components with molecular weights ranging from 20,000 to 130,000, and two contained largely a single component of molecular weight 130,000. Digestion of a single-component preparation with plasmin produced fragments with molecular weights similar to those found in the multicomponent preparations. Amino-terminal analysis, peptide mapping, and amino acid analysis showed that plasmin digestion generated a fragment of 20,000 molecular weight, which corresponded to a component present in a multicomponent ceruloplasmin preparation. The 20,000 molecular weight fragment appears to correspond to the so-called alpha-subunit or L-chain of human ceruloplasmin. Chemical evidence is thus provided that ceruloplasmin is a single-chain protein and that the so-called subunits are fragments. The 20,000 molecular weight fragment contains a single cysteine; amino acid sequence studies have shown that the sequence in the vicinity of this residue is similar to that around the single cysteine residue in plant plastocyanins and bacterial azurins, which are small, blue, copper-containing proteins.
已对通过不同方法制备的九份人铜蓝蛋白样本[铁（II）：氧氧化还原酶；EC 1.16.3.1]进行了异质性检测；凝胶电泳显示，七份样本含有多种分子量在20,000至130,000之间的成分，两份样本主要含有一种分子量为130,000的单一成分。用纤溶酶消化单一组分的制剂会产生分子量与多组分制剂中发现的分子量相似的片段。氨基末端分析、肽图谱分析和氨基酸分析表明，纤溶酶消化产生了一个分子量为20,000的片段，该片段对应于多组分铜蓝蛋白制剂中存在的一种成分。这个分子量为20,000的片段似乎对应于人铜蓝蛋白所谓的α亚基或L链。因此，有化学证据表明铜蓝蛋白是一种单链蛋白，所谓的亚基是片段。这个分子量为20,000的片段含有一个半胱氨酸；氨基酸序列研究表明，该残基附近的序列与植物质体蓝素和细菌天青蛋白中单个半胱氨酸残基周围的序列相似，植物质体蓝素和细菌天青蛋白是小型含铜蓝色蛋白。
