5-Ethyl-4-thiouridine

5-Ethyl-4-thiouridine is a modified pyrimidine nucleoside featuring a sulfur substitution at the 4-position and an ethyl group at the 5-position. This thionucleoside analog is utilized in biochemical research, including studies on tRNA structure and function, and serves as a probe in both in vitro and in vivo investigations of nucleic acid metabolism and modification.