Site-Specific Difunctionalization of Structured RNAs Yields Probes for microRNA Maturation.

Modified oligonucleotides bearing multiple functional labels are valuable tools in RNA biology. Efficient synthetic access to singly modified short DNAs and RNAs has been developed in the past years and paved the way to a first generation of oligonucleotide tools. Here, we describe an efficient procedure for the site-specific hetero bis-labeling of long RNAs. We exemplified the method with the preparation of Cy3/Cy5 pre-microRNAs labeled at selected internal sites as probes for microRNA maturation.