Properties of cytosolic components activating rat hepatic 5 - deiodination in the presence of NADPH
نویسندگان
چکیده
The effects of cytosol, NADPH and reduced glutathione (GSH) on the activity of 5'-deiodinase were studied by using washed hepatic microsomes from normal fed rats. Cytosol alone had little stimulatory effect on the activation of microsomal 5'-deiodinase. NADPH had no stimulatory effect on the microsomal 5'-deiodinase unless cytosol was added. 5'-deiodinase activity was greatly enhanced by the simultaneous addition of NADPH and cytosol (P < 0.001); this was significantly higher than that with either NADPH
منابع مشابه
On the role of NADPH and glutathione in the catalytic mechanism of hepatic thyroxine 5'-deiodination.
A possible metabolic linkage between hepatic thyroxine (T4) 5'-deiodination and the NADPH-glutathione (GSH) cycle was studied in rat liver. Supplementation of 1 mM NADPH to stocked liver homogenates in vitro produced 4 fold increase in 3, 5, 3'-triiodothyronine (T3) formation from T4, whereas the effect of 1 mM FMN, FDN, NAD, NADH, or GSH was relatively small. An exponential dose-response relat...
متن کاملEvidence for a single enzyme in rat liver catalysing the deiodination of the tyrosyl and the phenolic ring of iodothyronines.
The enzymic 5'-deiodination of 3',5'-di-iodothyronine and 5-deiodination of 3,3',5-tri-iodothyronine by rat liver microsomal fractions were found to be characterized by apparent Km values of 0.77 and 17.4 microM respectively, 3',5'-Di-iodothyronine was a competitive inhibitor of 3,3',5-tri-iodothyronine 5-deiodination (Ki 0.65 microM) and 3,3',5-tri-iodothyronine was a competitive inhibitor of ...
متن کاملProtective Effect of Wrightia Tinctoria Bark Triterpenoidal Fraction on Ccl4-Induced Acute Rat Liver Toxicity
The present investigation aims at assessing the hepatoprotective effect of triterpene fraction isolated from the stem bark of Wrightia tinctoria (containing lupeol, b -amyrin and b -sitosterol) on CCl 4 -induced hepatotoxicity in the rat. CCl 4 (1.5 mg/kg, i.p) is a potent hepatotoxic agent which causes peroxidative degeneration of membrane lipids with the potential outcome of fatt...
متن کاملInterspecies variation in the hepatic biotransformation of zearalenone: Evidence for bio-inactivation of mycoestrogen zearalenone in sturgeon fish
Zearalenone (ZEA) as mycoestrogen is found in human foods and animal feeds. Its estrogenic potency depends on its biotransformation fate. The hepatic biotransformation of ZEA in two species of sturgeon fish (Acipenser persicus and Huso huso) was investigated. ZEA was incubated with the hepatic microsomal and post-mitochondrial sub-fractions in the presence of NADPH and the metabolites were dete...
متن کاملInterspecies variation in the hepatic biotransformation of zearalenone: Evidence for bio-inactivation of mycoestrogen zearalenone in sturgeon fish
Zearalenone (ZEA) as mycoestrogen is found in human foods and animal feeds. Its estrogenic potency depends on its biotransformation fate. The hepatic biotransformation of ZEA in two species of sturgeon fish (Acipenser persicus and Huso huso) was investigated. ZEA was incubated with the hepatic microsomal and post-mitochondrial sub-fractions in the presence of NADPH and the metabolites were dete...
متن کامل