Synthesis and properties of deoxyoligonucleotides containing putrescinylthymine (nucleosides and nucleotides. LXXVI).

Putrescinylthymidine was prepared by the reduction of the Schiff base formed from a 2'-deoxy-5-formyluridine derivative and N-phthaloylputrescine, followed by deprotection. The following deoxyoligonucleotides containing putrescinylthymine (TP) were synthesized; dodecathymidylic acids containing two to four TP residues, self-complementary decanucleotides (AAGAATTCTT) and dodecanucleotides (AGATAGCTATCT) in which T residues were partly replaced by TP, and related oligomers. Oligonucleotides containing TP were resistant to nuclease S1 digestion and were poor substrates to venom phosphodiesterase. The thermal stability (Tm) of the duplex structure of oligomers containing TP was not enhanced in spite of the expected electrostatic binding between the putrescinyl and phosphoryl residues, and was rather sequence-dependent.