Nucleoside

This list does not include modified nucleobases and the corresponding nucleosides

The reason for 2 symbols, shorter and longer, is that the shorter ones are better for contexts where explicit disambiguation is superfluous (because context disambiguates) and the longer ones are for contexts where explicit disambiguation is judged to be needed or wise. For example, when discussing long nucleobase sequences in genomes, the CATG symbol system is much preferable to the Cyt-Ade-Thy-Gua symbol system (see Nucleic acid sequence § Notation for examples), but in discussions where confusion is likelier, the unambiguous symbols can be used.

Nitrogenous base	Ribonucleoside	Deoxyribonucleoside
adenine symbol A or Ade	adenosine symbol A or Ado	deoxyadenosine symbol dA or dAdo
guanine symbol G or Gua	guanosine symbol G or Guo	deoxyguanosine symbol dG or dGuo
thymine (5-methyluracil) symbol T or Thy	5-methyluridine (ribothymidine) symbol m⁵U	thymidine (deoxythymidine) symbol dT or dThd (dated: T or Thd)
uracil symbol U or Ura	uridine symbol U or Urd	deoxyuridine symbol dU or dUrd
cytosine symbol C or Cyt	cytidine symbol C or Cyd	deoxycytidine symbol dC or dCyd

Sources

Nucleosides can be produced from nucleotides

In medicine several nucleoside analogues are used as antiviral or anticancer agents.^[1][2][3][4] The viral polymerase incorporates these compounds with non-canonical bases. These compounds are activated in the cells by being converted into nucleotides. They are administered as nucleosides since charged nucleotides cannot easily cross cell membranes.

In molecular biology, several

In sequencing, dideoxynucleotides are used. These nucleotides possess the non-canonical sugar dideoxyribose, which lacks 3' hydroxyl group (which accepts the phosphate). DNA polymerases cannot distinguish between these and regular deoxyribonucleotides, but when incorporated a dideoxynucleotide cannot bond with the next base and the chain is terminated.

Prebiotic synthesis of ribonucleosides

In order to understand how life arose, knowledge is required of the chemical pathways that permit formation of the key building blocks of life under plausible prebiotic conditions. According to the RNA world hypothesis free-floating ribonucleosides and ribonucleotides were present in the primitive soup. Molecules as complex as RNA must have arisen from small molecules whose reactivity was governed by physico-chemical processes. RNA is composed of purine and pyrimidine nucleotides, both of which are necessary for reliable information transfer, and thus Darwinian natural selection and evolution. Nam et al.^[5] demonstrated the direct condensation of nucleobases with ribose to give ribonucleosides in aqueous microdroplets, a key step leading to RNA formation. Also, a plausible prebiotic process for synthesizing pyrimidine and purine ribonucleosides and ribonucleotides using wet-dry cycles was presented by Becker et al.^[6]

See also

• Arabinosyl nucleosides
• Nucleobase
• Salvage enzyme
• Synthesis of nucleosides

References