Reversible diselenide cross-links are formed between oligonucleotides containing 2′-deoxy-6-selenoinosine

We have synthesized and characterized a phosphoramidite derivative of 2'-deoxy-6-selenoinosine (d(6Se)I) and incorporated this modification into an oligonucleotide by solid-phase synthesis. During cleavage from the solid-support and deprotection, spontaneous dimerization of this oligonucleotide occurs via formation of a diselenide cross-link between the modified nucleobases. This cross-link can be readily reduced to restore the single-stranded oligonucleotide. UV thermal denaturation and circular dichroism spectroscopy of duplexes with d(6se)I paired against all four native nucleobases revealed minor differences in stability and structure relative to 2'-deoxyinosine. This selenium containing nucleobase modification may be useful for applications in DNA nanomaterials and X-ray crystallography. (C) 2017 Elsevier Ltd. All rights reserved.