This chemical, para-iodoHoechst 33258, is a derivative of Hoechst 33258 primarily used in biological research as a fluorescent stain for DNA. It binds specifically to the minor groove of double-stranded DNA, with a high affinity for AT-rich regions, making it a valuable tool for visualizing and quantifying DNA in various experimental setups. Researchers often employ it in fluorescence microscopy to study cell nuclei and chromosome structures. Additionally, it is utilized in flow cytometry to analyze DNA content in cells, aiding in studies related to cell cycle analysis and apoptosis. The para-iodo substitution enables photoactivatable crosslinking upon UV irradiation, allowing for the formation of covalent bonds with DNA-binding proteins. This feature makes it particularly useful for identifying specific DNA sequences, studying DNA-protein interactions, and investigating mechanisms in processes like transcription and replication.