[Mutagenesis directed by phosphotriester analogs of oligonucleotides]

20-mer oligodeoxyribonucleotides d-ACGACGG (R') CCAG (R'') TGATCCGTA, where R' = R'' = H (20), F' = Et, R'' = H (20-Et), or R' = R'' = Et (20-Et2) were synthesized by modified triester method. Ethylated dinucleotide blocks were prepared by transesterification method from chlorophenyl derivatives. Structures of oligonucleotides were confirmed by Maxam - Gilbert method. Mutagenesis induced by oligonucleotides was studied on DNA of M13mpB phage. Oligonucleotides were not totally complementary to this DNA in the region of 4-11 codons of Z'-gene. They all were shown to direct the formation of the designed deletion mutants, phosphotriester analogues (20-Et) and (20-Et2) being more effective mutagens. The specificity of oligonucleotides: DNA binding and mutant DNA structure were shown by Sanger method.