Visser T J, Frank S, Leonard J L
Mol Cell Endocrinol. 1983 Dec;33(2-3):321-7. doi: 10.1016/0303-7207(83)90177-6.
Propylthiouracil (PTU) and iodoacetate (IAc) partially inhibit the 5'-deiodination of 3,3',5'-triiodothyronine (rT3) in cerebral cortex, but PTU has no effect on the 5'-deiodination of thyroxine (T4). We now report that pretreatment of cerebral cortex microsomes with increasing concentrations of IAc or iodoacetamide inhibits the PTU-sensitive 5'-deiodination of rT3 with half-maximal inhibition at less than 1 microM IAc. PTU-insensitive 5'-deiodination of rT3 and T4 requires 100-1000-fold higher concentrations of IAc to achieve similar inhibition. Trypsinization decreases both 5'-deiodinating activities by greater than 90%. These data suggest that enzyme SH groups do not participate in the 5'-deiodination of T4 or rT3 by the PTU-insensitive pathway.
丙硫氧嘧啶（PTU）和碘乙酸盐（IAc）可部分抑制大脑皮层中3,3',5'-三碘甲状腺原氨酸（反T3，rT3）的5'-脱碘作用，但PTU对甲状腺素（T4）的5'-脱碘作用无影响。我们现在报告，用浓度不断增加的IAc或碘乙酰胺预处理大脑皮层微粒体，可抑制rT3的PTU敏感型5'-脱碘作用，在IAc浓度低于1微摩尔时抑制作用达到半数最大效应。rT3和T4的PTU不敏感型5'-脱碘作用需要浓度高100 - 1000倍的IAc才能达到类似的抑制效果。胰蛋白酶处理可使两种5'-脱碘活性降低90%以上。这些数据表明，酶的巯基不参与PTU不敏感途径介导的T4或rT3的5'-脱碘作用。
