2'-O-Methyl-2-thiouridine is a purine nucleoside analogue present in synthetic thermophilic bacterial tRNAs. 2'-O-Methyl-2-thiouridine is more selective for A than unmodified U.

8-Azaguanosine, a purine nucleoside analog, exhibits a broad spectrum of antitumor activity and is employed in the study of various tumor diseases.

Gastric mucin is a large glycoprotein which is thought to play a major role in the protection of the gastrointestinal tract from acid, proteases, pathogenic microorganisms, and mechanical trauma.