Fractionation of the sequence organization of human DNA by preparative HgCl2/Cs2SO4 density gradients.

Human DNA has been fractionated on preparative HgCl2/Cs2SO4 density gradients. Repetitious sequences are found in DNA components of all base compositions but the (G + C)-rich sequences are enriched for repetitive sequences in (A + T)-rich components are tandemly arranged; those in (G + C)-rich components tend to be interspersed with single copy sequences. It is concluded that the interspersed repetitious sequences have high (G + C) compositions.