Modification of rat liver iodothyronine 5′-deiodinase activity with diethylpyrocarbonate and Rose Bengal; Evidence for an active site histidine residue

Mol, Jan A.; Docter, R.; Hennemann, G.; Visser, Theo J.

doi:10.1016/0006-291x(84)91409-8

Cited by 40 publications

(8 citation statements)

References 25 publications

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“…Previous studies have shown that BrAcT3 is an excellent affinity label for the Dl enzyme (29,31,40). On the other hand, similar techniques were unsuccessful in achieving specific labeling of D3 in rat brain microsomes (35) (Fig.…”

Section: Discussionmentioning

confidence: 97%

“…BrAc [1251] T3 was synthesized from bromoacetylchloride and T3 as described previously (29). The product was purified on LH-20 Sephadex by elution with ethanol and purity verified by thin layer chromatography in ethyl acetate/glacial acetic acid (9:1), and the concentration of the product was determined from the specific activity of the T3 used in the starting material as described previously.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Type 3 lodothyronine deiodinase: cloning, in vitro expression, and functional analysis of the placental selenoenzyme.

Salvatore¹,

Low²,

Berry³

et al. 1995

J. Clin. Invest.

180

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Type 3 iodothyronine deiodinase (D3) catalyzes the conversion of T4 and T3 to inactive metabolites. It is highly expressed in placenta and thus can regulate circulating fetal thyroid hormone concentrations throughout gestation. We have cloned and expressed a 2.1-kb human placental D3 cDNA which encodes a 32-kD protein with a Km of 1.2 nM for 5 deiodination of T3 and 340 nM for 5' deiodination of reverse T3. The reaction requires DTT and is not inhibited by 6n-propylthiouracil. We quantitated transiently expressed D3 by specifically labeling the protein with bromoacetyl [12"'I T3. The KatIK. ratio for 5 deiodination of T3 was over 1,000-fold that for 5' deiodination of reverse T3. Human D3 is a selenoenzyme as evidenced by (a) the presence of an in frame UGA codon at position 144, (b) the synthesis of a 32-kD 75Se-labeled protein in D3 cDNA transfected cells, and (c) the presence of a selenocysteine insertion sequence element in the 3' untranslated region of the mRNA which is required for its expression. The D3 selenocysteine insertion sequence element is more potent than that in the type 1 deiodinase or glutathione peroxidase gene, suggesting a high priority for selenocysteine incorporation into this enzyme. The conservation of this enzyme from Xenopus laevis tadpoles to humans implies an essential role for regulation of thyroid hormone inactivation during embryological development. (J. Clin. Invest. 1995. 96:2421-2430

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Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Type 3 lodothyronine deiodinase: cloning, in vitro expression, and functional analysis of the placental selenoenzyme.

Salvatore¹,

Low²,

Berry³

et al. 1995

J. Clin. Invest.

180

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“…(15). All deiodinase reactions were stopped by adding 100 ILL pooled human serum and 500 IxL ice-cold 10% TCA.…”

Section: Methodsmentioning

confidence: 99%

Thyroid function and deiodinase activities in rats with marginal iodine deficiency

Janssen

Heide

Visser

et al. 1994

Biol Trace Elem Res

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The hypothesis tested was whether marginal iodine deficiency for a period of 6 wk affects iodothyronine deiodinase activities in liver and brain of rats. Male rats were fed purified diets either defident or sufficient in iodine; the diets were fed on a restricted basis (60% of ad libitum intake). Body weight gain of the two groups was comparable, Iodine deficiency was evidenced by increased thyroid weight (26%), reduced urinary iodine excretion (80%), and reduced plasma T4 concentrations (22%). Activities of liver type I and brain type III deiodinase were unchanged, but the activity of type I] deiodinase in brain was increased (28%) in the iodine-deficient rats. Food restriction per se significantly lowered T 3 (30%) and I"4 (22%) concentrations in plasma and decreased type III deiodinase activity in brain (30%). These results indicate that in marginal iodine deficiency the activities of hepatic type I deiodinase and brain type III deiodinase are unchanged, whereas that of brain type II deiodinase is increased.Index Entries: Rats; iodine deficiency; food restriction; thyroid; deiodination; liver; brain.*Author to whom all correspondence and reprint requests should be addressed. Biological Trace Element Research 237VoL 40. I ~94

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“…The influence of SAM (10-1000MuM) (14) in 0.1 M phosphate buffer (pH 7.2), 2 mM EDTA, and 5 mM dithiothreitol (DTT). The free fractions of rT3 and 3,3Y-T2 in incubation medium were determined by equilibrium dialysis.…”

Section: Methodsmentioning

confidence: 99%

Metabolism of reverse triiodothyronine by isolated rat hepatocytes.

Rooda¹,

Loon²,

Tj³

1987

J. Clin. Invest.

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Reverse triiodothyronine (rT3) is metabolized predominantly by outer ring deiodination to 3,3'-diiodothyronine (3,3'-T2) in the liver. Metabolism of rT3 and 3,3'-T2 by isolated rat hepatocytes was analyzed by Sephadex LH-20 chromatography, high performance liquid chromatography, and radioimmunoassay, with closely agreeing results. Deiodinase activity was inhibited with propylthiouracil (PTU) and sulfotransferase activity by sulfate depletion or addition of salicylamide or dichloronitrophenol. Normally, little 3,3'-T2 production from rT3 was observed, and 1251 was the main product of both 3,13'-'25iT2 and 13',5'-25IlrT3. PTU inhibited rT3 metabolism but did not affect 3,3'-T2 clearance as explained by accumulation of 3,3'-T2 sulfate. Inhibition of sulfation did not affect rT3 clearance but 3,3'-T2 metabolism was greatly diminished. The decrease in I formation from rT3 was compensated by an increased recovery of 3,3'-T2 up to 70% of rT3 metabolized. In conclusion, significant production of 3,3'-T2 from rT3 by rat hepatocytes is only observed if further sulfation is inhibited.

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Modification of rat liver iodothyronine 5′-deiodinase activity with diethylpyrocarbonate and Rose Bengal; Evidence for an active site histidine residue

Cited by 40 publications

References 25 publications

Type 3 lodothyronine deiodinase: cloning, in vitro expression, and functional analysis of the placental selenoenzyme.

Type 3 lodothyronine deiodinase: cloning, in vitro expression, and functional analysis of the placental selenoenzyme.

Thyroid function and deiodinase activities in rats with marginal iodine deficiency

Metabolism of reverse triiodothyronine by isolated rat hepatocytes.

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