转铁蛋白结构与功能的研究——骆驼血清转铁蛋自的分离纯化及其含单一铁结合部位的结构域的制备和鉴定

分离纯化获得的骆驼血清转铁蛋白由分子量为73,000和63,000两个组分组成。两者至少N-端五肽顺序相同(Met-Pro-Asp-Lys-Thr)。骆驼血清转铁蛋白在生理pH下不能与人胎盘转铁蛋白受体结合。用胰蛋白酶酶解骆驼转铁蛋白可以同时得到两个合单一铁结合部位的结构域,分别来自转铁蛋白分子的N-端称N-端结构域(分子量34,700和40,700)和C-端称C-端结构域(分子量35,100)。在上述结果的基础上指出并讨论了反刍动物转铁蛋白在结构和功能上存在更多的共同性,而与其它哺乳动物的转铁蛋白有着明显的区别。

STUDIES ON THE STRUCTURE AND FUNCTION OF TRANSFERRIN-ISOLATION AND PURIFICATION OF CAMEL SERUM TRANSFERRIN AND PREPARATION AND CHARACTERIZATION OF DOMAINS CONTAINING A SINGLE IRON-BINDING SITE IN THE TRANSFERRIN

Carnel serum transferrin (CTf) was purified from camel serum by the means of ammonium sulfate fractionation and Chromatography with DE-52 column. The CTF consists of two components with molecular weight of 73,000 and 63,000 respectively and there are at least 5 amino acid sequence(Met-Pro-Asp-Lys-Thr) in N-ter-minal of them are homogeneous. CTf does not bind with human transferrin receptor on human placenta at physiological pH.The N-and C-domains with moecular weight of 34,700 and 35,100 respectively were simultaneously obtained from trypsin digest by the use of gel filtration with Sephadex G-75 column and affinity chromatography with ConA-Sepharose-4B. Each domain contains a single iron binding site and retains iron binding capacity.On the basis of comparative study with bovine and sheep transferrins we suggest that transferrins from ruminant animals may have more common features in structure and function which are apparently different from those of the other mammalian transferrins.