Preliminary chemical and X-ray studies on the interactions of E. coli DNA with putrescine.

The interactions of E.coli DNA with putrescine in aqueous solution and fiber were studied by melting temperature analysis, equilibrium dialysis and X-ray diffraction. The equilibrium binding of putrescine to DNA is shown, of which association constant is in the order of 10(3) 1/mol. The binding of putrescine stabilizes the B-form of DNA fiber and the crossbridge of putrescine in the intra-double helix is suggested by precipitate formation experiments of various polyamines with DNA.