Biochemical Studies on Polyamine and its Analogues

Preincubation with spermine, of λ T 7 and P 465 phages which were sensitive to oxidized spermine, resulted in a decrease of their susceptibility to the action of oxidized spermine. Phages resistant to oxidized spermine such as T 4 and ϕX 174 became susceptible to this agent after dialysis. The mechanism of phagocidal action of oxidized spermine was examined with 32P-labelled λ phage. Oxidized spermine interfered neither with the absorption of λ phage, nor with the injection of its DNA into the host cells. The injected DNA, however, did not lead to the formation of mature phage. The interaction of oxidized spermine with the DNA of phages T 4 and T 7 was investigated by thermal denaturation studies. DNA treated with oxidized spermine showed the same Tm as untreated DNA. However, the treated DNA was decreased in its hyperchromicity and was renatured to a great extent, even after rapid cooling. These facts are explained by the formation of cross-links which prevents the separation of complementary DNA strands.