A new usage of functionalized oligodeoxynucleotide probe for site-specific modification of a guanine base within RNA

Site-specific modification of RNA is of great significance to investigate RNA structure, function and dynamics. Recently, we reported a new method for sequence- and cytosine-selective chemical modification of RNA based on the functional group transfer reaction of the 1-phenyl-2-methylydene-1,3-diketone unit of the 6-thioguanosine base incorporated in the oligodeoxynucleotide probe. In this study, we describe that the functionality transfer rate is greatly enhanced and the selectivity is shifted to the guanine base when the reaction is performed under alkaline conditions. Detailed investigation indicated that the 2-amino group of the enolate form of rG is the reactant of the functionality transfer reaction. As a potential application of this efficient functionality transfer reaction, a pyrene group as a relatively large fluorescent group was successfully transferred to the target guanine base of RNA with a high guanine and site selectivity. This functionality transfer reaction with high efficiency and high site-selectivity would provide a new opportunity as a unique tool for the study of RNA.