A study of the interaction of histones with DNA using isopycnic centrifugation in metrizamide gradients

Isopycnic sedimentation in metrizamide gradients has shown that mouse-liver histones bind co-operatively to both homologous and bacterial DNA's. However, at low input ratios of histone to DNA, two types of stable complex are formed, depending on the histone concentration. One complex contains half as much histone as DNA while the other contains approximately equal amounts of histone and DNA. At high input ratios of histone to DNA extra histone is bound giving complexes containing up to twice as much histone as DNA. Poly-L-lysine and protamine were also found to bind co-operatively to DNA.