Synthesis and NMR applications of isotopically labeled 2'-deoxynucleosides. Stereospecific deuteration of the C2' methylene in [ul-11 C/15N]deoxyadenosine.

Stereospecific deuteration of the C2' methylenes of 2'-deoxynucleosides together with 13C label has been found to open up various applications for structural studies of DNA oligomers in solution. Major problems in analyzing the structure and dynamics of larger DNA oligomers by NMR are associated with geminal proton pairs attached to the C2' and C5' of sugar moieties. We have employed, with a minor modification, existing synthetic routes to prepare stereospecific deuteration of the C2' methylene to prepare 13C/2H-doubly labeled nucleosides. For example, [ul-13C/15N] adenosine, which was prepared by microbial fermentation using [13C6]-glucose and [15N]-ammonium salt as precursors, was derived into (2'R)- and (2'S)-[ul-13C/15N;2'-2H1]-2'-deoxy-adenosines. Each of these multiply labeled nucleosides was then incorporated into a DNA dodecamer, 5'-d(CGCG AATTCGCG)-3', which was examined by various NMR techniques in order to evaluate the precision and accuracy of the NMR parameters obtained for the labeled moieties.