bromouridine

Bromouridine, commonly referred to as 5-bromouridine, is a halogenated nucleoside analog of uridine in which a bromine atom replaces hydrogen at the 5-position of the uracil ring. It is a ribonucleoside consisting of a uracil base linked to a beta-D-ribofuranose sugar.

Chemically, bromouridine can be prepared by electrophilic bromination of uridine at the 5-position, typically using brominating reagents such as N-bromosuccinimide under protective conditions to minimize side reactions and allow subsequent deprotection to yield the free nucleoside. It is soluble in water and stable under standard laboratory storage conditions.

In molecular biology, bromouridine is used as an analog of uridine to label newly synthesized RNA. When cells are supplied with bromouridine, it can be incorporated into RNA in place of uridine during transcription. Bromouridine-containing RNA can be detected with antibodies against brominated nucleosides, often anti-BrdU antibodies, after appropriate processing. This labeling approach underpins methods such as Bru-seq and related BrU immunoprecipitation techniques that map transcriptional activity and RNA dynamics on a genome-wide or gene-specific scale. Bromouridine can also be phosphorylated to bromouridine triphosphate (BrUTP) and used by RNA polymerases in in vitro transcription assays.

Safety and handling follow standard precautions for halogenated nucleosides. Bromouridine can be cytotoxic at high concentrations and should be handled with appropriate personal protective equipment and waste disposal practices in accordance with institutional guidelines.