Effects of methimazole on the 5'-monodeiodinase activities of various tissues.
Iodothyronine 5'-deiodinases were assayed in preparations of liver, cerebral cortex and brown adipose tissue. Rate profiles at various pH values revealed that methimazole activates the liver enzyme (type I) and inhibits the enzyme from brown adipose tissue (type II). Other results show that the type II enzyme may be activated by methimazole when the concentration of endogenous sulfhydryl cofactor or of dithiothreitol in the system is low. Collectively, these results suggest an interplay between the sulfhydryl (-SH) tautomer of methimazole and the sulfhydryl activators of the enzymes.
Zenker
N
N
Department of Medicinal Chemistry and Pharmacognosy, School of Pharmacy, University of Maryland, Baltimore.
Hubbard
L S
LS
Tildon
J T
JT
D002001:Adipose Tissue, Brown / Q000201:enzymology*; D000818:Animals; D002540:Cerebral Cortex / Q000201:enzymology*; D007453:Iodide Peroxidase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008713:Methimazole / Q000494:pharmacology*; D008862:Microsomes, Liver / Q000201:enzymology*; D011441:Propylthiouracil / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D013965:Thyroidectomy
D008713:Methimazole; D011441:Propylthiouracil; D007453:Iodide Peroxidase