Synthetic analogues of polynucleotides. Part VIII. 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.