Stimulation of RNA polymerases I, II and III from rat liver by spermine, and specific inhibition of RNA polymerase I by higher spermine concentrations.

Spermine stimulates activities of higherly purified rat liver nuclear RNA olymerases I, II and III 3 to 4 fold. Inclusion of (NH4)2SO4 at concentrations required for maximal enzyme activities does not significantly enhance the degree of stimulation of polymerase activities by spermine, but maintains the stimulatory levels of enzymes over a broader range of spermine concentrations. The stimulatory effect of spermine at a concentration of 1 mM is a useful method for the elevation of activities of all RNA polymerases and thus provides a means to measure these enzymes when extracted from small quantities of tissues or cells. Based on the differential stimulation of the polymerases by spermine, a higher concentration of spermine (5 mM) can be selected to inhibit RNA polymerase I specifically.