Synthetic analogues of polynucleotides. 8. Analogues of oligonucleotides containing carboxymethylthymidine.

Abstract

Analogues of oligonucleotides in which the nucleoside units are linked by acetate ester linkages (·O·CH2·CO2·) instead of the phosphodiester linkages of the natural compounds, have been synthesised. The compounds obtained were thymidinylacetyl-(3′→5′)-thymidinylacetyl-(3′→5′)-thymidinylacetyl-(3′→5′)-uridine, thymidinylacetyl-(3′→5′)-thymidinylacetyl-(3′→5′)-thymidinylacetyl-(3′→5′)-thymidinylacetyl-(3′→5′)-uridine, and thymidinylacetyl-(3′→5′)-thymidinylacetyl-(3′→5′)-thymidinylacetyl-(3′→5′)-thymidinylacetyl-(3′→5′)cytidine. The last was also obtained labelled with tritium in the cytidine residue. An oligomer of similar structure to these compounds having a molecular weight between 4 × 103 and 4.7 × 104 was obtained by copolymerising 3′-O-carboxymethylthymidine with 0.1 mol. equiv. of 2′,3′-O-isopropylideneuridine and removing the blocking group. This oligomer and the other two uridine-containing oligomers gave a small but significant hypochromic effect when mixed with polyadenylic acid in solution.