[Chemical reactions in double-stranded nucleic acids. V. Directed introduction into the DNA sugar-phosphate backbone of aliphatic diamine or glycol residues].

The chemical ligation method was used for directed introduction of aliphatic diamines or glycols into sugar-phosphate backbone of DNA. Via condensation of heptanucleotide derivatives at the terminal phosphate (aminoalkylamides or hydroxyalkyl esters) with the adjacent heptanucleotide on the corresponding template, 14 bp DNA duplexes containing residues of ethylene-, propylene- or hexamethylenediamine, as well as residues of ethylene- or propyleneglycol in one of its strands, were synthesised. In a similar way duplexes were obtained in which residues of the above diamines or glycols are substituted for a mononucleotide in one of the complementary strands. Examplified by synthesis of DNA duplexes containing ethylenediamine or ethyleneglycol residues, three methods of the phosphate group activation using carbodiimide, imidazolide and N-hydroxybenzotriazole ester were tested; the last method gave the highest yields and purity of the products. Yields of duplexes without nucleotide omissions were 50, 36 and 7% for aminoethyl, aminopropyl and aminohexylamides, and 20 and 17% for hydroxyethyl and hydroxypropyl esters, respectively, whereas duplexes with nucleotide omissions were synthesised with lower yields. Each of the modified DNA duplexes thus obtained contains a recognition site of EcoRII, SsoII or MvaI restriction nucleases, thus being a potential substrate of these enzymes.