Biochem J. 1975 Sep;150(3):489-93. doi: 10.1042/bj1500489.
By using a highly specific radioimmunoassay the formation of tri-iodothyronine by the deiodination of thyroxine was studied in rat liver homogenate. Several observations suggest that the reaction observed is enzymic in nature. Pre-heating the homogenate for 30 min at 56 degrees C completely abolished conversion of thyroxine into tri-iodothyronine; the component of rat liver homogenate responsible could be saturated with substrate; iodotyrosines displayed competitive activity. Between 0 degrees and 37 degrees C, the tri-iodothyronine-production rate was positively correlated with incubation temperature. The addition of NAD+ enhanced conversion into tri-iodothyronine, which suggests that an oxidative mechanism is involved. 5-Propyl-2-thiouracil and 6-propyl-2-thiouracil, both known to prevent deiodination in vivo, greatly decreased the deiodiantion activity of rat liver homogenate.
通过使用高度特异性的放射免疫分析法,研究了大鼠肝脏匀浆中甲状腺素脱碘形成三碘甲状腺原氨酸的过程。多项观察结果表明,所观察到的反应本质上是酶促反应。将匀浆在56℃预热30分钟可完全消除甲状腺素向三碘甲状腺原氨酸的转化;大鼠肝脏匀浆中起作用的成分可被底物饱和;碘酪氨酸具有竞争活性。在0℃至37℃之间,三碘甲状腺原氨酸的生成速率与孵育温度呈正相关。添加NAD⁺可增强向三碘甲状腺原氨酸的转化,这表明涉及氧化机制。5-丙基-2-硫脲嘧啶和6-丙基-2-硫脲嘧啶,已知二者均可在体内阻止脱碘,它们可大大降低大鼠肝脏匀浆的脱碘活性。