EFFICIENT ASSESSMENT OF MODIFIED NUCLEOSIDE STABILITY UNDER CONDITIONS OF AUTOMATED OLIGONUCLEOTIDE SYNTHESIS: CHARACTERIZATION OF THE OXIDATION AND OXIDATIVE DESULFURIZATION OF 2-THIOURIDINE

Abstract

In order to efficiently assess the chemical stability of modified nucleosides to the reagents and conditions of automated oligonucleotide synthesis, we designed, developed and tested a scheme in which the modified nucleoside, directly attached to a solid support, is exposed to the cyclic chemistry of the instrument. Stability of 2-thiouridine against different oxidizers was investigated. Tertbutyl hydroperoxide (1 M) in anhydrous acetonitrile was a more effective oxidizer for the incorporation of 2-thiouridine into oligonucleotide chains than the same oxidizer in methylene chloride. Carbon tetrachloride/water in the presence of a basic catalyst was superior in maintaining the thiocarbonyl function, but its utility for RNA synthesis has yet to be fully tested, whereas 2-phenylsulfonyloxaziridine was a very efficient reagent for oxidative desulfurization of 2-thiouridine.

ACKNOWLEDGMENTS

I thank Paul F. Agris and Richard Guenther (NCSU) and Andrzej Małkiewicz (Technical University of Łódź) for helpful discussions and comments on manuscript.

I also thank Winnell Newman of the NCSU Nucleic Acids Facility for the help in the experiments on oligonucleotide synthesizer.

This work was supported by the Polish Commitee for Scientific Research, Grant no. 0877/T09/96/11, and a National Science Foundation Grant, MCB9986011.