Visser T J, Does-Tobé I, Docter R, Hennemann G
Biochem J. 1976 Aug 1;157(2):479-82. doi: 10.1042/bj1570479.
Experiments with rat liver homogenates showed that on subcellular fractionation the ability to catalyse the conversion of thyroxine into tri-iodothyronine was lost. The activity could in part be restored by addition of the cytosol to the microsomal fraction. Both components were found to be heat labile. The necessity of the presence of cytosol could be circumvented by incorporation of thiol-group-containing compounds in the medium. Optimal enzymic activity was observed in the presence of dithiothreitol and EDTA in medium of low osmolarity. By comparing the distribution of the converting enzyme over the subcellular fractions with a microsomal marker enzyme, glucose 6-phosphatase, it was demonstrated that the former is indeed of microsomal origin. Finally, it was shown that thiol groups play an essential role in the conversion of thyroxine into tri-iodothyronine.
对大鼠肝脏匀浆进行的实验表明,在亚细胞分级分离时,催化甲状腺素转化为三碘甲状腺原氨酸的能力丧失。通过向微粒体部分添加胞质溶胶,该活性部分得以恢复。发现这两种成分都对热不稳定。通过在培养基中加入含硫醇基团的化合物,可以避免胞质溶胶存在的必要性。在低渗透压培养基中,在二硫苏糖醇和乙二胺四乙酸存在的情况下观察到最佳酶活性。通过将转化酶在亚细胞部分的分布与微粒体标记酶葡萄糖6-磷酸酶进行比较,证明前者确实起源于微粒体。最后,结果表明硫醇基团在甲状腺素转化为三碘甲状腺原氨酸的过程中起重要作用。