Selenium modification of nucleic acids: preparation of oligonucleotides with incorporated 2'-SeMe-uridine for crystallographic phasing of nucleic acid structures.

This protocol describes a method for introducing an anomalously scattering atom into oligonucleotides at the 2'-position of uridine by conventional solid-phase synthesis. The 2'-SeMe ribose modification is particularly attractive for derivatization of RNA to facilitate crystal structure determination. The estimated time for the synthesis and HPLC purification of oligonucleotides with incorporated 2'-SeMe-uridine residues is approximately 46 h for 'trityl on' and approximately 32 h for 'trityl off' methods, respectively.