Atomic Force Microscopy Study of Ganglioside GM1 Concentration Effect on Lateral Phase Separation of Sphingomyelin/ Dioleoylphosphatidylcholine/Cholesterol Bilayers

摘要

The effect of monosialoganglioside GM1 (GM1) concentration on the lateral phase separation in the sphingomyelin/1,2-dioleoyl-sn-glycero-3-phosphocholine/ cholesterol (SM/DOPC/Chol) bilayers was studied by using atomic force microscopy. The results show that, with the increase of GM1 mol fraction (x), the dominant composition of liquid-ordered (L0) domains changes from SM to SM/GM1 and finally to GM1. Meanwhile, the decrease of domain area (A) of the L_o phase with the increase of x follows a scaling law of A ～ x ~(3/2) , for x > 0.005, indicating that the domain growth is pinned with high GM1 concentration. Results of in situ experiments of GM1 insertion into SM/DOPC/cholesterol bilayers further supported our observations.