Glycosides and Nucleotides

Glycosides are compounds in which the substituent is bound to the anomeric carbon. This group comprises numerous natural products the primary metabolites. The most important are nucleosides, the basic structural units from which nucleotides and nucleic acids are formed. The monosaccharide component of the nucleoside is D-ribose or its partially reduced form D-deoxyribose. In biochemistry and molecular biology the most important are the nucleosides in which ribose is bonded to heterocyclic molecules called nucleic bases. The most common nucleic bases are pyrimidines and purines. 

Pyrimidines are derivatives of the cyclic amine pyrimidine while purines are derived from the bicyclic amine purine. 

The glycoside that consists of adenine and D-ribose (in its cyclic form ribofura-nose) is adenosine. 

In biochemical systems, adenosine appears as a phosphate in three forms, as adenosine monophosphate (AMP), adenosine diphosphate (ADP) and adenosine triphosphate (ATP). These phosphate esters of nucleosides are called nucleotides and they are the basic building blocks of nucleic acids DNA and RNA, the compounds which are carriers of genetic information. 

In an enzyme catalyzed reaction, ATP can be hydrolyzed by losing one phosphate group P04 , with the release of large amount of energy that has been accumulated in the P-0 bond. This reaction serves as the source of energy for the processes in living cells. 

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