[Complementarily addressed alkylation and cleavage of T7 phage DNA adjacent to the oligothymidylic sequences]

Effect of temperature and reagent excess on the alkylation of the T7 phage DNA by an alkylating derivative of hexaadenylate that containes a modifying group on the 3'-terminus has been studied. Under condition of saturation at 20 degrees the reagent covalently binds adjacent to the 133 5'-PuN2--4Tn greater than or equal to 4 sequences in the T7 DNA; at 40 degrees the reagent alkylates 24 5'-PuN2Tn greater than or equal to 6 sequences. DNA containing specific apurinic sites has been prepared due to elimination of the alkylated purines. This DNA has been cleaved at the apurinic sites and specific DNA fragments have been obtained. Three types of DNA fragments are formed due to alkylation at 20 degrees: one fragment with 26,500 nucleotides in length, seven fragments with 4500 nucleotides in length and 103--111 fragments with an average length of 190 nucleotides. Alkylation at 40 degrees with following apurinization and cleavage yields 21--23 fragments with the lengths: 1--31,500; 1--19,000; 3--9500 and 17--19 with 1100 nucleotides in average.