Synthesis of β-Diketone DNA Derivatives for Affinity Modification of Proteins

Diketone DNA derivatives have been proposed to modify the guanidine group of Arg in proteins. The β-diketo group at the C2' atom of the sugar phosphate moiety has been introduced in DNA by acylation of oligonucleotide precursors, i.e., DNA fragments containing 2'-amino-2'-deoxyuridine, which have been synthesized by the chemical automatic synthesis. Water-soluble N -[3-(dimethylamino)propyl]- N ′-ethylcarbodiimide (EDC) and 4,6-dioxoheptanoic acid have been used in the reaction. The ability of oligodeoxyribonucleotides containing the 2'-β-diketo group to react with guanidine, N α -Boc- L -arginine, and N α -Dns- L -arginine has been demonstrated. The introduction of this modification into one of the strands of the 15-base pair DNA duplex has been shown to lead to its destabilization. The conjugate formation of MutS and MutL proteins from the E. coli mismatch repair system with 17-base pair DNA duplexes containing the 2'-deoxy-2'-(4,6-dioxoheptylamido)uridine residue has been detected for the first time. To increase the selectivity of the DNA ligands containing the β-diketo group in the reaction with the Arg residues of proteins, we have proposed to treat the reaction mixture with hydroxylamine. This treatment leads to the cleavage of Schiff bases, which are formed with the involvement of lysine residues.