Spermine is a polyamine involved in cellular metabolism found in all eukaryotic cells. The precursor for synthesis of spermine is the amino acid ornithine. It is found in a wide variety of organisms and tissues and is an essential growth factor in some bacteria. It is found as a polycation at physiological pH. Spermine is associated with nucleic acids and is thought to stabilize helical structure, in particular, in viruses.