Chemistry of Nucleotides

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Figure 12.1 Purine bases.
Figure 12.2 Adenosine and deoxyadenosine.
12.3— Chemistry of Nucleotides
The major purine derivatives in cells are those of adenine and guanine. Other purine bases encountered are hypoxanthine and xanthine (Figure 12.1). Nucleoside derivatives of these molecules will contain either ribose or 2­deoxyribose linked to the purine ring through a b ­N­glycosidic bond at N­9. Ribonucleosides contain ribose, while deoxyribonucleosides contain deoxyribose as the sugar moiety (Figure 12.2). Nucleotides are phosphate esters of purine nucleosides (Figure 12.3). 3 ­
Nucleotides such as adenosine 3 ­monophosphate (3 ­AMP) may occur in cells as a result of nucleic acid degradation. In normally functioning cells, tri­ and diphosphates are found to a greater extent than monophosphates, nucleosides, or free bases.
Figure 12.3 Adenine nucleotides.