Figure 5.

(a) Synchrotron XRD measurements of the isoelectric Φ_DOPC = 0.6 complexes with trivalent polyamine spermidine chloride. Spermidine causes DNA condensation in 2D (DNA correlation peak indicated with dashed lines) at 11.9 mM, and at higher concentration also removes DNA out of the complexes into a coexisting phase of spermidine-condensed 3D DNA with hexagonal symmetry (solid arrow at 14 mM). Solid line shows a SAXS scan of pure bulk DNA condensed with ≈14 mM of spermidine (without lipids) and proves that the extra peak in 14 mM complex scan is caused by the coexisting spermidine-DNA phase. (b) Variation of d_DNA in complexes with spermidine and spermine. Also shown is the DNA spacing a in the bulk spermidine and spermine condensed DNA phase.