[Chemical transformation of radioactive 4-(N-2-chloroethyl-N-methylamino)benzyl-5'-[32P]phosphamides of oligodeoxyribonucleotides during in vivo experiments].

The practical use of reactive oligonucleotide derivatives for complementarily addressed modification of nucleic acids in vivo includes several steps, at which side chemical reactions resulting in a decrease of the modification efficiency may take place. Chemical reactions of 4-(N-2-chloroethyl-N-methylamino)benzyl-5'-[32P]phosphamides of oligodeoxyribonucleotides were studied in vivo. The intermolecular self-alkylation at the reactive residue of the alkylating derivative was found in the precipitate of its lithium salt under acetone at-20 degrees C. The effects of pH, buffer solutions, salts, temperature, phenol, cell culture suspensions, tissue homogenates, etc., on the stability of the derivatives were studied. A sufficient cleavage of the phosphamide bond was observed at pH less than 3. In fresh liver homogenates the nucleolytic degradation of the oligonucleotide part of the reagent was shown to occur. After intraperitoneal injection of mice with radioactive alkylating derivatives up to 50% of the reagent was included into the blood biopolymers within one hour. The covalently linked to the biopolymers oligonucleotide appeared to be highly degraded thereby.