Tabachnick M, Perret V
Department of Biochemistry, New York Medical College, Valhalla 10595.
Biochem Int. 1987 Aug;15(2):409-17.
[125I] Thyroxine has been covalently bound to the thyroxine binding site in thyroxine-binding globulin by reaction with the bifunctional reagent, 1,5-difluoro-2,4-dinitrobenzene. An average of 0.47 mol of [125I] thyroxine was incorporated per mol protein; nonspecific binding amounted to 8%. A labeled peptide fragment was isolated from a proteolytic digest of the derivatized protein by HPLC and its amino acid composition was determined. Comparison with the amino acid sequence of thyroxine-binding globulin indicated partial correspondence of the labeled peptide with two possible regions in the protein. These regions also coincide with part of the barrel structure present in the closely homologous protein, alpha 1-antitrypsin.
通过与双功能试剂1,5-二氟-2,4-二硝基苯反应，[125I]甲状腺素已共价结合到甲状腺素结合球蛋白的甲状腺素结合位点上。每摩尔蛋白质平均掺入0.47摩尔[125I]甲状腺素；非特异性结合量为8%。通过高效液相色谱法从衍生化蛋白质的蛋白水解消化物中分离出一个标记的肽片段，并测定了其氨基酸组成。与甲状腺素结合球蛋白的氨基酸序列比较表明，标记肽与该蛋白质中两个可能的区域部分对应。这些区域也与紧密同源的蛋白质α1-抗胰蛋白酶中存在的桶状结构的一部分重合。
