Ability of clionasterol and poriferasterol (24-epimers of sitosterol and stigmasterol) to regulate membrane lipid dynamics
Résumé
Stigmasterol and sitosterol, which are the major sterols contained in plasma membranes of plant cells have been shown to possess a different ordering ability: stigmasterol is less efficient than sitosterol for regulating membrane permeability and fluidity. We have evaluated the activity of their C-24 epimers on model membranes systems by 2H-NMR. Clionasterol was found to be as efficient as sitosterol; in contrast, poriferasterol appeared to be less efficient than its epimer, stigmasterol. The modification of the configuration at C-24 has thus an influence on the sterol ordering ability in the case of a coexistence of the Δ12 double bond and the ethyl group, i.e. in the stigmasterol series.