Abstract
Herein we describe the first simple and short method for specific labeling of mono- and trimethylated dinucleotide mRNA cap analogues with (13)C and (14)C isotopes. The labels were introduced within the cap structures either at the N7 for monomethylguanosine cap or N7 and N2 position for trimethylguanosine cap. The compounds designed for structural and biochemical studies will be useful tools for better understanding the role of the mRNA cap structures in pre-mRNA splicing, nucleocytoplasmic transport, translation initiation and mRNA degradation.