Figure 5.

(A) TEs of DOTAP/DOPC/steroid–DNA complexes. The TE data for ergosterol 2 and ergocalciferol 3 follows a similar dependence on the steroid content in the membrane as that of cholesterol 1: TE rapidly increases with Φsteroid. In contrast, addition of β-estradiol 4, progesterone 5 and dehydroisoandrosterone 6 only modestly enhances TE until high steroid contents (35 mol% and higher) are reached, where phase separation occurs (cf. Fig. 7) and TE suddenly increases to values comparable with TE of cholesterol-containing complexes. The major structural differences between these two groups of molecules are the absence of the terminal alkyl chain and the presence of a second polar moiety in case of 4–6. (B) Chemical structure of the investigated steroid molecules.