Levi S, Salfeld J, Franceschinelli F, Cozzi A, Dorner M H, Arosio P
Department of Biomedical Sciences and Technology, University of Milan, Ospedale San Raffaele, Milano, Italy.
Biochemistry. 1989 Jun 13;28(12):5179-84. doi: 10.1021/bi00438a040.
The human ferritin L-chain cDNA was cloned into a vector for overproduction in Escherichia coli, under the regulation of a lambda promoter. The plasmid obtained contains the full L-chain coding region modified at the first two codons. It is able to direct the synthesis of the L-chain which can constitute up to 15% of the total soluble protein of bacterial extract. The L-chains assemble to form a ferritin homopolymer with electrophoretic mobility, molecular weight, thermal stability, spectroscopic, and immunological properties analogous to natural ferritin from human liver (95% L-chain). This recombinant L-ferritin is able to incorporate and retain iron in solution at physiological pH values. At variance with the H-ferritin, the L form does not uptake iron at acidic pH values and does not show detectable ferroxidase activity. It is concluded that ferritin L-chain lacks the ferroxidase site present in the H-chain and that the two chains may have specialized functions in intracellular iron metabolism.
人铁蛋白L链cDNA被克隆到一个载体中，以便在大肠杆菌中过量表达，受λ启动子调控。所获得的质粒含有在前两个密码子处修饰的完整L链编码区。它能够指导L链的合成，L链可占细菌提取物总可溶性蛋白的15%。L链组装形成一种铁蛋白同聚物，其电泳迁移率、分子量、热稳定性、光谱学和免疫学特性与来自人肝脏的天然铁蛋白（95%为L链）相似。这种重组L-铁蛋白能够在生理pH值下在溶液中摄取并保留铁。与H-铁蛋白不同，L型在酸性pH值下不摄取铁，也没有可检测到的铁氧化酶活性。得出的结论是，铁蛋白L链缺乏H链中存在的铁氧化酶位点，并且这两条链在细胞内铁代谢中可能具有专门的功能。
