Deoxyribose
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Image:Deoxyribose.png
Deoxyribose, also known as D-Deoxyribose and 2-deoxyribose, is an aldopentose — a monosaccharide containing five carbon atoms, and including an aldehyde functional group. It is derived from the pentose sugar ribose by the replacement of the hydroxyl group at the 2 position with hydrogen, leading to the net loss of an oxygen atom, and has chemical formula C{{#if:{{{1|}}}|{{{1}}}|}}5H{{#if:{{{1|}}}|{{{1}}}}}10O{{#if:{{{1|}}}|{{{1}}}|}}4.
Ribose forms a five-member ring composed of four carbon atoms and one oxygen. Hydroxyl groups are attached to three of the carbons. The other carbon and a hydroxyl group are attached to one of the carbon atoms adjacent to the oxygen. In deoxyribose, the carbon furthest from the attached carbon is stripped of the oxygen atom in what would be a hydroxyl group in ribose.
One of the common bases is adenine (a purine derivative); coupled to ribose it is called adenosine; coupled to deoxyribose it is called deoxyadenosine. The 5′-triphosphate derivative of adenosine, commonly called ATP, for adenosine triphosphate, is an important energy transport molecule in cells.
See Nucleic acid nomenclature for a diagram showing the numbered positions in a 5′-monophosphate nucleotide.
2-Deoxyribose and ribose nucleotides are often found in unbranched 5′-3′ polymers. In these structures, the 3′carbon of one monomer unit is linked to a phosphate that is attached to the 5′carbon of the next unit, and so on. These polymer chains often contain many millions of monomer units. Since long polymers have physical properties distinctly different from those of small molecules, they are called macromolecules. The sugar-phosphate-sugar chain is called the backbone of the polymer. One end of the backbone has a free 5′phosphate, and the other end has a free 3′OH group. The backbone structure is independent of which particular bases are attached to the individual sugars.
Genetic material in earthly life often contains poly 5′-3′, 2′-deoxyribose nucleotides, in structures called chromosomes, where each monomer is one of the nucleotides deoxy- adenine, thymine, guanine or cytosine. This material is commonly called deoxyribonucleic acid, or simply DNA for short.
DNA in chromosomes forms very long helical structures containing two molecules with the backbones running in opposite directions on the outside of the helix and held together by hydrogen bonds between complementary nucleotide bases lying between the helical backbones. The lack of the 2′ hydroxyl group in DNA appears to allows the backbone the flexibility to assume the full conformation of the long double-helix, which involves not only the basic helix, but additional coiling necessary to fit these very long molecules into the very small volume of a cell nucleus.
In contrast, very similar molecules, containing ribose instead of deoxyribose, and known generically as RNA, are known to form only relatively short double-helical complementary base paired structures. These are well known, for instance, in ribosomal RNA molecules and in transfer RNA (tRNA), where so-called hairpin structures form from palindromic sequences within one molecule.
See also
et:Desoksüriboos es:Desoxirribosa eo:Desoksiribozo fr:Désoxyribose it:Desossiribosio lt:Dezoksiribozė mk:Деоксирибоза nl:Deoxyribose ja:デオキシリボース pl:Deoksyryboza sv:Deoxiribos