CHEMICAL-REACTIONS IN DOUBLE-STRANDED NUC LEIC-ACIDS .16. SYNTHESIS OF DNA-DUPLEXES WITH REGULARLY REPEATED CROSS-LINKINGS

Two self-complementary decadeoxyribonucleotides TAATGC ATTA (where C* is a derivative of 5-methyl cytosine with a carboxy- or aminofunction attached through a spacer to the exocyclic amino group) were synthesi zed. Carbodiimide induced condensation of the amino and carboxyl group s in the opposite strands to give the crosslinks with a yield up to 20 %. Cross-linking of two opposite strands in the duplex formed by the s elf-complementary aliphatic amino group-containing decanucleotide was performed with the use of glutaric aldehyde with a similar efficiency. The structure of the dimers obtained and position of the crosslinks w ere confirmed by the Maxam-Gilbert method. Efficiencies of the T4 DNA ligase-induced polycondensations of the double-stranded modified decan ucleotides and of the cross-linked products differed significantly.