【项目简介】
Human Transferrin (Tf) is a single chain, 80 kDa member of the anionbinding superfamily of proteins. It is a bilobed molecule that is the product of an ancient gene duplication event. Transferrin is synthesized as a 698 amino acid (aa) precursor that is divided into a 19 aa signal sequence plus a 679 aa mature segment that contains 19 intrachain disulfide bonds. The crystal structure of Tf reveals a protein with two flanking 340 aa globular domains. Each are composed of a β-sheet surrounded by series of α-helices. The N-and C-terminal flanking regions (or domains) will bind ferric iron through the interaction of an obligate anion (usually bicarbonate) and four amino acids (His, Asp, and two Tyr). Apotransferrin (or ironfree) will initially bind one atom of iron at the Cterminus, and this is followed by subsequent iron-binding by the N-terminus to form holotransferrin (diferric Tf). Through its Cterminal iron-binding domain, holotransferrin will interact with the type I Tf receptor (TfR) on the surface of cells where it is internalized into acidified endosomes. Iron dissociates from the Tf molecule within these endosomes, and is transported into the cytosol as ferrous iron.
 
【检验原理】
本试剂盒采用双抗体夹心ELISA法。酶标微孔板上预包被有抗人Transferrin抗体，当加入标准品和待测样本时，标准品和待测样本中的人Transferrin会和该抗体结合。洗板后，游离的其他成分被洗去，加入辣根过氧化物酶标记的的抗人Transferrin抗体可与被酶标板捕获的人Transferrin结合，形成“包被抗人Transferrin抗体+人Transferrin+抗人Transferrin抗体-HRP”免疫复合物。当加入TMB显色底物后，复合物上连接的HRP催化底物反应，生成蓝色产物，终止反应后变为黄色。在450nm处测定OD值，人Transferrin浓度与OD450值之间呈正比，可通过绘制标准曲线求出标本中人Transferrin的浓度。