Interaction of oxidized polyamines with DNA. V. Inhibition of nucleic acid synthesis

1. 1. Oxidized spermine, an iminodialdehyde, obtained by the enzymic oxidation of spermine, inhibits the incorporation of labeled thymidine, and uracil into the nucleic acids of growing Escherichia coli cells. The incorporation of labeled valine into bacterial proteins is arrested only after a definite lag period. 2. 2. Oxidized spermine also inhibits nucleic acid synthesis in cell-free systems, using purified DNA-dependent RNA polymerase and DNA polymerase. The inhibition of DNA synthesis by oxidized spermine, is somewhat greater than that of RNA synthesis. 3. 3. The inhibition of nucleic acid synthesis is due to the binding of oxidized spermine to the DNA primer and not to its interaction with the nucleoside triphosphates or the enzymes. 4. 4. Inhibition of DNA replication by oxidized spermine is dependent on the nature of the DNA used and is higher when guanine-cytosine-rich primers are used.