Preparation of 2'-deoxy-2'-methylseleno-modified phosphoramidites and RNA.

The derivatization of nucleic acids with selenium is a useful approach to facilitate phase determination during three-dimensional structural analysis by X-ray crystallography. This unit describes (1) the synthesis and characterization of 2'-deoxy-2'-methylseleno (2'-Se-methyl) nucleosides and their corresponding 3'-O-(2-cyanoethyl)-N,N-diisopropylphosphoramidite derivatives, (2) the site-specific incorporation of 2'-Se-methyl ribonucleosides into oligoribonucleotides by chemical RNA solid-phase synthesis, and (3) the enzymatic ligation of Se-containing RNA oligonucleotides to produce a biologically relevant RNA sequence.