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|Section2= |Section3= }} Dihydrouridine (abbreviated as D, DHU, or UH2) is a pyrimidine which is the result of adding two hydrogen atoms to a uridine, making it a fully saturated pyrimidine ring with no remaining double bonds. D is found in tRNA and rRNA molecules as a nucleoside; the corresponding nucleobase is 5,6-dihydrouracil. Because it is non-planar, D disturbs the stacking interactions in helices and destabilizes the RNA structure. D also stabilizes the C2’-''endo'' sugar conformation, which is more flexible than the C3’-''endo'' conformation, and this effect is propagated to the 5’-neighboring residue. Thus, while pseudouridine and 2’-O-methylations stabilize the local RNA structure, D does the opposite.〔 〕 tRNA of organisms that grow at low temperatures (psychrophiles) have high 5,6-dihydrouridine levels (40-70% more on average) which provides the necessary, local, flexibility of the tRNA at or below the freezing point.〔 〕 == References == 〔 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「Dihydrouridine」の詳細全文を読む スポンサード リンク
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