Different thyroid hormone‐deiodinating enzymes in tilapia (Oreochromis niloticus) liver and kidney

FEBS Letters

Kühn, Eduard R.³  Visser, Theo J.¹  de Greef, Wim J.²  Darras, Veerle M.³  Kaptein, Ellen¹  Mol, Koen³ 

[1] Department of Internal Medicine III, Erasmus University Medical School, 3000 DR Rotterdam, The Netherlands;Department of Endocrinology and Reproduction, Erasmus University Medical School, 3000 DR Rotterdam, The Netherlands;Laboratory of Comparative Endocrinology, Catholic University of Leuven, B-3000 Leuven, Belgium

关键词: Thyroid hormone;    Iodothyronine;    Deiodination;    Fish;    Rat;    Liver;    Kidney;    Selenocysteine;    Propylthiouracil;    lodoacetate;    Aurothioglucose;   

DOI  :  10.1016/0014-5793(93)80095-C

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Enzymes catalyzing the outer ring deiodination (ORD) of iodothyronines are important for the regulation of thyroid hormone bioactivity. We have studied ORD of thyroxine (T4) and 3,3',5'-triiodothyronine (rT3) in liver and kidney microsomes offish, i.e. tilapia (Oreochromis niloticus). Tilapia kidney contains an enzyme which resembles the mammalian selenoenzyme type I iodothyronine deiodinase (ID-I) with respect to substrate preference (rT3 > T4) and high (≈ μM) K _m values, but is much less sensitive to selenocysteine (Sec)-targeted inhibitors, including 6-propyl-2-thiouracil (PTU). In contrast, tilapia liver contains an enzyme very similar to mammalian type II deiodinase (ID-II) with respect to substrate preference (T4 > rT3), low (≈ nM) K _m values, and lack of sensitivity to Sec inhibitors.

【 授权许可】

Unknown