Guanosine

Guanosine is a purine nucleoside consisting of guanine attached to a ribose sugar by a beta-N9-glycosidic bond. It is one of the nucleosides present in ribonucleic acid (RNA) and serves as a component of ribonucleotides that participate in cellular metabolism and genetic information storage and expression.

In RNA, guanosine pairs with cytosine through hydrogen bonding, contributing to the structure and stability of RNA molecules. The corresponding deoxyribonucleoside is deoxyguanosine, which is found in deoxyribonucleic acid (DNA). Guanosine can be phosphorylated to form GMP, GDP, and GTP, which are involved in energy transfer, signaling, and the synthesis and function of RNA and proteins.

Biosynthesis and salvage of guanosine occur through several pathways. In salvage pathways, guanine is converted to GMP by guanine phosphoribosyltransferase (GPRT) using phosphoribosyl pyrophosphate (PRPP). De novo GMP synthesis proceeds from inosine monophosphate (IMP) via GMP synthetase. Guanosine can be produced by dephosphorylation of GMP or by enzymatic release from nucleotides.

Degradation of guanosine yields guanine and ribose, with guanine subsequently catabolized or rescued in salvage pathways. Guanosine is also used in biochemical research and is commercially available for studies of purine metabolism, nucleoside transport, and related processes.