Nucleic Acids Research, 2003, Vol. 31, No. 19 5685-5691
© 2003 Oxford University Press
3'-Modified oligonucleotides by reverse DNA synthesis
Department of Chemistry and Department of Biology, University of Virginia, Charlottesville, VA 22901, USA
*To whom correspondence should be addressed. Tel: +1 434 924 3906; Fax: +1 434 924 7856; Email: sidhecht{at}virginia.edu
This paper is dedicated to the memory of our friend and colleague Professor Claude Hélène, in appreciation of his seminal contributions to nucleic acid chemistry and biochemistry
Reverse DNA oligonucleotide synthesis (i.e. from 5'
3') is a strategy that has yet to be exploited fully. While utilized previously for the construction of alternating 3'-3'- and 5'-5'-linked antisense oligonucleotides, the use of nucleoside 5'-phosphoramidites has not generally been used for the elaboration of (modified) oligonucleotides. Presently, the potential of reverse oligonucleotide synthesis for the facile synthesis of 3'-modified DNAs is illustrated using a phosphoramidite derived from tyrosine. The derived oligonucleotide was shown to have chromatographic and electrophoretic properties identical with the modified oligonucleotide resulting from the proteinase K digestion of the vaccinia topoisomerase I–DNA covalent complex. The results confirm the nature of the structure previously assigned to this product, and establish the facility with which proteinase K is able to complete the digestion of the polypeptide backbone of the DNA oligonucleotide-linked topoisomerase I.