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|Section2= |Section6= |Section7= }} Riboflavin (vitamin B2) is part of the vitamin B group. It is the central component of the cofactors FAD and FMN and as such required for a variety of flavoprotein enzyme reactions including activation of other vitamins. It was formerly known as vitamin G. Riboflavin is a yellow-orange solid substance with poor solubility in water. It is best known visually as it imparts the color to vitamin supplements and the yellow color to the urine of persons taking it. The name "riboflavin" comes from "ribose" (the sugar whose reduced form, ribitol, forms part of its structure) and "flavin", the ring-moiety which imparts the yellow color to the oxidized molecule (from Latin ''flavus'', "yellow"). The reduced form, which occurs in metabolism along with the oxidized form, is colorless. == Function == The active forms Flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) function as cofactors for a variety of flavoproteine enzyme reactions: * Flavoproteins of electron transport chain, including FMN in Complex I and FAD in Complex II * FAD is required for the production of pyridoxic acid from pyridoxal (vitamin B6) by pyridoxine 5'-phosphate oxidase * The primary coenzyme form of vitamin B6 (pyridoxal phosphate) is FMN dependent * Oxidation of pyruvate, α-ketoglutarate, and branched-chain amino acids requires FAD in the shared E3 portion of their respective dehydrogenase complexes * Fatty acyl CoA dehydrogenase requires FAD in fatty acid oxidation * FAD is required to convert retinol (vitamin A) to retinoic acid via cytosolic retinal dehydrogenase * Synthesis of an active form of folate (5-methyltetrahydrofolate) from 5,10-methylenetetrahydrofolate by Methylenetetrahydrofolate reductase is FADH2 dependent * FAD is required to convert tryptophan to niacin (vitamin B3) * Reduction of the oxidized form of glutathione (GSSG) to its reduced form (GSH) by Glutathione reductase is FAD dependent For the molecular mechanism of action see main articles Flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「riboflavin」の詳細全文を読む スポンサード リンク
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