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|Section2= |Section3= }} Phytoene (FY-toe-een) is a 40-carbon intermediate in the biosynthesis of carotenoids.〔(Carotenoid Biosynthesis )〕 The synthesis of phytoene is the first committed step in the synthesis of carotenoids in plants. Phytoene is produced from two molecules of geranylgeranyl pyrophosphate (GGPP) by the action of the enzyme phytoene synthase.〔(Phytoene synthase )〕 The two GGPP molecules are condensed together followed by removal of diphosphate and proton shift leading to the formation of phytoene. Dietary phytoene and phytofluene are found in a number of human tissues including the liver, lung, breast, prostate, colon, and skin.〔Khachik F, Carvalho L, Bernstein PS, Muir GJ, Zhao DY, Katz NB. Chemistry, distribution, and metabolism of tomato carotenoids and their impact on human health. Experimental biology and medicine. 2002;227:845-51.〕 Accumulation of these carotenoids in the skin may protect the skin by several mechanisms: acting as UV absorbers, as antioxidants, and as anti-inflammatory agents. == Structure == Phytoene is a symmetric molecule containing three conjugated double bonds. Phytoene has a UV-Vis absorption spectrum ''typical'' for a triply conjugated system with its main absorption maximum in the UVB range at 286 nm and with ''ε1% of 915''. 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「phytoene」の詳細全文を読む スポンサード リンク
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