[Circular dichroism spectra of DNA complexes with stellins A and B--protamines from Acipenser stellatus]

The circular dichroism (CD) spectra of DNA complexes with stellins A and B, protamines from Acipenser stellatus, in 2,5 x 10(-4) M EDTA were studied. The CD spectrum of the stellin B--DNA complex practically coincides with that of original DNA. In the CD spectrum of the stellin A--DNA complex the positive band amplitude increases at 275 nm, while the negative band amplitude decreases at 245 nm at increasing of protein/DNA ratio. The resulting A-like CD spectrum is apparently coupled with the changes in the parameters of DNA double helix. The changes in the CD spectra in the stellin A--DNA complex are correlated with a higher capacity of stellin A for helix formation in ethanol. The data obtained suggest that individual components of stellin play a specific role in the structural organization of nucleoprotamine.