Ribonucleotides, furanose ring

Nucleic acids are linear polymers of nucleotides linked 3 to 5 by phosphodi-ester bridges (Figure 11.17). They are formed as 5 -nucleoside monophosphates are successively added to the 3 -OH group of the preceding nucleotide, a process that gives the polymer a directional sense. Polymers of ribonucleotides are named ribonucleic acid, or RNA. Deoxyribonucleotide polymers are called deoxyribonucleic acid, or DNA. Because C-1 and C-4 in deoxyribonucleotides are involved in furanose ring formation and because there is no 2 -OH, only... 

The conversion of ribonucleotides into deoxyribonucleotides for the synthesis of DNA is key to the survival of any DNA-based life form. This process is completed by one of a variety of ribonucleotide reductases that reduce the furanose ring of a ribonucleic diphosphate acid monomer by replacing a hydroxyl functional group at the 2 -position with a hydrogen (Scheme 6) to generate the deoxyribonucleic acid... 

Nucleic acids have two kinds of pentoses. The recurring deoxyribonucleotide units of DNA contain 2 -deoxy-D-ribose, and the ribonucleotide units of RNA contain D-ribose. In nucleotides, both types of pentoses are in their j3-furanose (closed five-membered ring) form. As Figure 8-3 shows, the pentose ring is not planar but occurs in one of a variety of conformations generally described as puckered. ... 

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