The replication of DNA II. The number of polynucleotide strands in the conserved unit of DNA.

The kinetics of degradation of DNA by deoxyribonuclease II have been studied, using the techniques of light scattering, viscosity, and titration. Theoretical equations have been derived for both random and non-random attacks, and all assumptions have been evaluated. It has been shown that these equations permit a valid calculation of the number of polynucleotide strands per molecule. The results have been verified by two independent experimental methods. DNA from proliferating sources was found to be four-stranded; DNA from non-proliferating sources was found to be two-stranded. The implications of these findings are discussed.