Structural heterogeneity of reconstituted complexes of DNA with typical and intermediate protamines.

The binding of the intermediate proteins phi 1 and phi 3 from the mussel Mytilus edulis to DNA was studied in comparison with the typical protamine from the squid Loligo vulgaris using precipitation curves, thermal denaturation and X-ray diffraction techniques. The properties of protein phi 1 appear to be very close to those of typical protamines while the properties of protein phi 3 are notably different. The method of reconstitution influences the structural properties of the complexes. This effect is most pronounced in the case of protein phi 3. The structural heterogeneity of the protein component in the complexes is discussed in the light of these observations.