adenosine

A combination of adenine with D-ribose, a pentose sugar. The two molecules are linked by a β-glycosidic bond and together form a *nucleoside . Adenine may alternatively combine with 2-deoxy-D-ribose, in which case the nucleoside is called deoxyadenosine. The latter is the form found in DNA, while adenosine is found in RNA, ATP, ADP, and AMP. Certain derivatives of adenosine (e.g. isopentenyl adenosine or *IPA ) are cytokinins. See also nucleotide .