Sutherland R L, Simpson-Morgan M W
J Endocrinol. 1975 Jun;65(3):319-32. doi: 10.1677/joe.0.0650319.
A competitive binding technique is described for the estimation of the thyroxine (T4)-binding properties of serum proteins in dilute blood serum and lymph. When used in conjunction with an assay for total T4 the following parameters can be estimated: the number of functionally different T4 binding proteins, their individual association constants and binding capacities for T4, the amount of T4 which is bound to each binding species, and the concentration of unbound (free) T4. Both human and sheep serum have three functionally different T4-binding proteins. The association constants for the three human proteins were 9.5x10(9), 1.6x10(8) and 3.1x10(5) 1/mol for T4-binding globulin (TBG), T4-binding prealbumin (TBPA) and serum albumin, respectively. The corresponding sheep proteins, TBG, TBP-2 and albumin, had association constants of 8.9x10(9), 1-4 X 10(8) and 3.5x10(5) 1/mol. Human TBG had a mean binding capacity of 21.3 mug/100 ml and that of ovie TBG was 12.8 mug/100 ml. The other specific binding proteins (TBPA in man and TBP-2 in sheep) had mean binding capacities of 307 and 359 mug/100 ml respectively. Two functionally different T4-binding proteins were identified in rat serum.
本文描述了一种竞争性结合技术，用于评估稀血清和淋巴中血清蛋白的甲状腺素（T4）结合特性。当与总T4测定法结合使用时，可估算以下参数：功能不同的T4结合蛋白的数量、它们各自的结合常数和对T4的结合能力、与每种结合类型结合的T4量以及未结合（游离）T4的浓度。人和羊的血清均有三种功能不同的T4结合蛋白。三种人蛋白与T4结合球蛋白（TBG）、T4结合前白蛋白（TBPA）和血清白蛋白的结合常数分别为9.5×10⁹、1.6×10⁸和3.1×10⁵ 1/mol。相应的羊蛋白，即TBG、TBP-2和白蛋白，其结合常数分别为8.9×10⁹、1.4×10⁸和3.5×10⁵ 1/mol。人TBG的平均结合能力为21.3μg/100ml，羊TBG的平均结合能力为12.8μg/100ml。其他特异性结合蛋白（人血清中的TBPA和羊血清中的TBP-2）的平均结合能力分别为307和359μg/100ml。在大鼠血清中鉴定出两种功能不同的T4结合蛋白。
