Oligonucleotide duplexes containing 2′-amino-2′-deoxycytidines: thermal stability and chemical reactivity

Thermal stabilities of oligonucleotides containing 2'-amino-2'-deoxycytidines were determined and compared to those of the unmodified oligonucleotides. The presence of the 2'-aminonucleoside destabilized duplexes in a RNA as well as a DNA context at pH 7 as well as at pH 5. The pKa of the 2'-amino group was determined by 13C-NMR spectroscopy to be 6.2. The reactivity of an oligonucleotide containing a 2'-aminonucleoside was exploited for the incorporation of rhodamine by its isothiocyanate derivative.