Selective coupling of a highly basic peptide to an oligonucleotide

Abstract

A highly basic peptide (net charge +8) derived from the HIV-1 Tat protein is conjugated with quantitative yield within minutes to a 19 mer rhodamine,labelled phosphodiester oligonucleotide activated by the pyridine sulfenyl group. To avoid precipitation due to antagonist charges of the oligonucleotide and the peptide the conjugation was performed with high salt concentration (400mM) and acetonitrile (40%).