Synthesis of β-Diketone DNA Derivatives for Affine Modification of Proteins
Diketone DNA derivatives were proposed to modify the guanidine group of Arg in proteins. β-Diketo group at the C2''-atom of the sugar-phosphate moiety was introduced in DNA by acylation of oligonucleotide precursors – DNA fragments with 2''-amino-2''-deoxyuridine, obtained by chemical automatic synthesis. The 4,6-dioxoheptanoic acid and water-soluble 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) were used in the reaction. The ability of oligodeoxyribonucleotides containing 2''-β-diketo group to react with guanidine, N<sup>α</sup> -Boc-L-arginine and N<sup>α</sup>-Dns-L-arginine was demonstrated. It is shown that the introduction of such a modification into one of the strand of 15-mer DNA duplex leads to its destabilization. The conjugate formation of MutS and MutL proteins from E. coli mismatch repair system with 17-mer DNA duplexes containing the 2''-deoxy-2''-(4,6-dioxoheptylamido)uridine residue was detected for the first time. To increase the selectivity of DNA ligands with the β-diketo group in reaction with Arg residues of proteins, it has been proposed to treat the reaction mixture with hydroxylamine solution. Such treatment leads to destruction of Schiff-bases formed with the lysine residue participation.