Nonenzymatic Deiodination of Thyroid Hormones by Flavin Mononucleotide and Light

Stopped flow studies on the nonenzymatic reduction of methemoglobin by reduced flavin mononucleotide.

The nonenzymatic reduction of methemoglobin by the reduced form of flavin mononucleotide was studied under various conditions by following the reaction with a stopped flow apparatus. The reaction was very fast, compared with the reduction of the flavin by NADPH-flavin reductase of human erythrocytes, and followed a second order rate law: the rate constant (K) for the reduction of methemoglobin ...

Biomimetic deiodination of thyroid hormones and iodothyronamines - a structure-activity relationship study.

Mammalian selenoenzymes, iodothyronine deiodinases (DIOs), catalyze the tyrosyl and phenolic ring deiodination of thyroid hormones (THs) and play an important role in maintaining the TH concentration throughout the body. These enzymes also accept the decarboxylated thyroid hormone metabolites, iodothyronamines (TAMs), as substrates for deiodination. Naphthalene-based selenium and/or sulphur-con...

Flavin mononucleotide enzyme electrode amplified by a bioelectrocatalytic cycle.

Purification of flavin mononucleotide-dependent enzymes by column chromatography on flavin phosphate cellulose compounds.

The chemical syntheses of monoand dimethyl esters of riboflavin phosphate were accomplished by allowing riboflavin to react with the appropriate monoand dimethylchlorophosphoric acids. Riboflavin monomethyl phosphate was found to be coenzymatically active with nicotinamide adenine dinucleotide phosphate-cytochrome c aporeductase, pyridoxine (or pyridoxamine) phosphate apooxidase, and glycolate ...

Caffeic acid inhibits the formation of 7-carboxyheptyl radicals from oleic acid under flavin mononucleotide photosensitization by scavenging singlet oxygen and quenching the excited state of flavin mononucleotide.

We examined the effects of caffeic acid (CA) and related compounds on 7-carboxyheptyl radical formation. This analysis was performed using a standard D2O reaction mixture containing 4.3 mM oleic acid, 25 μM flavin mononucleotide (FMN), 160 mM phosphate buffer (pH 7.4), 10 mM cholic acid, 100 mM α-(4-pyridyl-1-oxide)-N-tert-butylnitrone, and 1 mM Fe(SO4)2(NH4)2 during irradiation with 7.8 J/cm2 ...