Effect of polyamines on purified poly(ADP-ribose) synthetase from rat liver nuclei

Using the purified enzyme system, we investigated the spermine-induced stimulation of poly(ADP-ribose) formation. In the presence of 2 microgram DNA and 10 mM Mg2+ in a reaction mixture of 0.2 ml, the optimal concentrations of spermine, spermidine and putrescine were 10, 12.5 and 35 mM, respectively. With the omission of Mg2+, there was an increase in optimal concentrations of polyamines without changes in the rate of poly(ADP-ribose) formation. The concentrations of spermine required for maximum synthesis of poly(ADP-ribose) were increased in proportion to the increase in the amount of DNA. Kinetic analysis of poly(ADP-ribose) formation showed a decrease in Km values for NAD with the addition of spermine. The possible relationship of polyions with regard to DNA, spermine and histone in the purified enzyme system was discussed.