adeninenucleoside

Adeninenucleoside, commonly referred to as adenosine in English, is a nucleoside consisting of the purine base adenine attached to a ribose sugar by a beta-N9-glycosidic bond. When the sugar component is deoxyribose instead of ribose, the corresponding nucleoside is deoxyadenosine. The ribonucleoside form is the one found in RNA and is typically simply called adenosine.

Chemically, adenosine consists of the adenine base linked to the 1′ carbon of the beta-D-ribofuranose. The molecule has the formula C10H13N5O4 and, in biological systems, serves as a fundamental building block of nucleic acids and a precursor to important energy carriers.

Biological roles include functioning as a component of RNA, where adenosine residues encode genetic information and participate in RNA metabolism. Adenosine is also a key intermediate in cellular energy transfer, existing in the phosphorylated forms AMP, ADP, and ATP. Extracellular adenosine acts as a signaling molecule, binding to adenosine receptors (A1, A2A, A2B, A3) to influence processes such as vasodilation, neurotransmission, and inflammation.

Metabolism involves salvage and degradation pathways. Adenosine can be formed from AMP by 5′-nucleotidases, or generated during RNA turnover. It is deaminated to inosine by adenosine deaminase and ultimately degraded to uric acid or recycled via purine salvage pathways that involve PRPP and phosphoribosyltransferases.

Clinically, adenosine is used as a pharmacological agent to terminate certain supraventricular tachycardias due to its transient effects on the AV node.