Inosine

Inosin.svg

Inosine is a nucleoside that is formed when hypoxanthine is attached to a ribose (also known as a ribofuranose) ring via a β-N9-glycosidic bond. Inosine is commonly found in transfer RNA (tRNA) and is essential for proper translation of the genetic code in wobble base pairs.

Structure and Properties

Inosine consists of a purine base, hypoxanthine, linked to a ribose sugar. The chemical formula of inosine is C10H12N4O5. It is a white, crystalline powder that is soluble in water.

Biological Role

Inosine plays a crucial role in various biological processes. It is involved in the purine metabolism pathway and can be converted into adenosine and guanosine nucleotides. Inosine is also a key component in the inosine monophosphate (IMP) pathway, which is critical for the synthesis of adenosine triphosphate (ATP) and guanosine triphosphate (GTP).

Inosine in tRNA

Inosine is found in the anticodon of some tRNAs, where it can pair with adenine, cytosine, or uracil in the wobble position of the codon. This flexibility allows for the proper translation of the genetic code and increases the efficiency of protein synthesis.

Medical Applications

Inosine has been studied for its potential therapeutic effects in various medical conditions. It has been investigated for its role in neuroprotection, immune modulation, and cardioprotection. Some studies suggest that inosine may help in the treatment of multiple sclerosis, Parkinson's disease, and stroke.

Metabolism

Inosine is metabolized in the body by the enzyme purine nucleoside phosphorylase (PNP) to produce hypoxanthine and ribose-1-phosphate. Hypoxanthine can then be further metabolized to xanthine and uric acid.

Dietary Sources

Inosine can be found in various dietary sources, including meat, fish, and dairy products. It is also available as a dietary supplement.

See Also

• Nucleoside
• Purine metabolism
• Transfer RNA
• Adenosine
• Guanosine
• Hypoxanthine