Evidence for the bilobal nature of diferric rabbit plasma transferrin
Evidence for the bilobal nature of diferric rabbit plasma transferrin
复制标题
双铁兔血浆转铁蛋白双叶性质的证据
作者：
B. Gorinsky;C. Horsburgh;P. Lindley;D. Moss;M. Parkar;J. Watson
血浆转铁蛋白参与脊椎动物循环系统内的铁运输，并为血红蛋白合成和其他代谢需求提供铁源。然而，尽管光谱、生化和生理技术进行了广泛的研究，但对铁结合的性质以及铁的摄取和释放机制仍不完全清楚。血浆转铁蛋白1是一种相对分子质量约为80,000的单体糖蛋白。2)；它们与Fe(III)有两个相似且非常强的结合部位，以及两个相关的阴离子结合部位。对不同转铁蛋白3-6的裂解研究表明，多肽链由多肽链的N-末端和C-末端两个部分组成。每个结构域包含一个金属结合位点。这两个部分之间存在的显著序列相似性可能反映了在蛋白质2，7的系统发育过程中一个祖先结构基因的加倍。本实验室已报道了兔血浆转铁蛋白的初步结晶学研究。我们现在报告了对二铁性兔血浆转铁蛋白的X射线结构测定的初步研究，这导致了6-Å分辨率的电子密度图。
Plasma transferrin is involved in iron transport within the circulatory system of vertebrates, and provides an iron source for haemoglobin synthesis and other metabolic requirements. However, despite extensive studies by spectroscopic, biochemical and physiological techniques, the nature of iron binding and the mechanisms of uptake and release of iron are not fully understood. Plasma transferrins1 are monomeric glycoproteins with a molecular weight of approximately 80,000 (ref. 2); they have two similar and very strong binding sites for Fe(III), together with two associated anion binding sites. Fragmentation studies on various transferrins3–6 have shown that the polypeptide chain is composed of two domains formed from the N-terminal and C-terminal halves of the polypeptide chain. Each domain contains one metal binding site. The marked sequence similarities which exist between the two halves may reflect a doubling of an ancestral structural gene during the phylogenetic development of the protein2,7. Preliminary crystallographic investigations of diferric rabbit plasma transferrin have been reported from this laboratory8. We now report initial studies of the X-ray structure determination of diferric rabbit plasma transferrin which have led to a 6-Å resolution electron density map.