Dihydrouridine

• D ( short code )
• 1- β -D - ribofuranosyl -1 ,3- diazinan -2 ,4 -dione
• 1 - [( 2R, 3R, 4S, 5R ) -3,4- dihydroxy-5- (hydroxymethyl) oxolane -2-yl ] -1,3- diazinan -2 ,4 -dione
• 5,6- dihydrouridine

Fixed

Template: Infobox chemical / molecular formula search available

Dihydrouridine (D, U H2, Uh) is a nucleoside and occurs in tRNA, rRNA, snRNA and chromosomal RNA. It consists of the β -D - ribofuranose (sugar) and the nucleobase dihydrouracil. It is formed by adding two hydrogen atoms to uridine, so that a fully saturated ring formed without double bonds.

Properties

Dihydrouridine forms a base pair with adenosine.

The ring is due to the lack of double bond is not planar and thus more flexible. Dihydrouridine significantly destabilizes the C3' - endo conformation of the sugar, which is necessary for the formation of A-type helical RNA. However dihydrouridine favors the C2'- endo conformation of the sugar, it is more flexible than the C3'-endo conformation. It is to be found a greater conformational flexibility and dynamic motion in regions of RNA where tertiary interactions and loop formation are required simultaneously. So while pseudouridine and 2'-O- methylation to stabilize the local RNA structure, this is the opposite at dihydrouridine.

In the tRNA dihydrouridine is quite common, and due to the frequent occurrence in a section of a part of the tRNA is called Dihydrouracil-Arm/-Schleife.

A tRNAAla from S. cerevisiae. Dihydrouracil is featured here with D.

TRNA from organisms that grow at low temperatures ( psychrophiles ) have high 5,6- dihydrouridine levels (40-70 % more than the average), which provide the necessary local flexibility of the tRNA at or below freezing.