Abstract
Small-angle neutron scattering (SANS) and dynamic light scattering (QLS) are used to characterize the aggregates found upon dilution of mixed lecithin-bile salt micelles. Molar ratios of lecithin (L) to taurocholate (TC) studied varied from 0.1 to 1, and one series contained cholesterol (Ch). Mixed aggregates of L and taurodeoxycholate (TDC) at ratios of 0.4 and 1 were also examined. In all cases the micelles are cylindrical or globular and elongate upon dilution. The radius of the mixed micelles varies only slightly with the overall composition of lecithin and bile salt which indicates that the composition of the cylindrical micelle body is nearly constant. The transition from micelles to vesicles is a smooth transformation involving a region where micelles and vesicles coexist. SANS measurements are more sensitive to the presence of two aggregate populations than QLS. Beyond the coexistence region the vesicle size and degree of polydispersity decrease with dilution. Incorporation of a small amount of cholesterol in the lipid mixture does not affect the sequence of observed aggregate structures.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1733-1742 |
| Number of pages | 10 |
| Journal | Biophysical journal |
| Volume | 67 |
| Issue number | 4 |
| DOIs | |
| State | Published - 1994 |
Bibliographical note
Funding Information:Supported in part by the Division of Materials Sciences, U.S. Department of Energy, under contract DE-AC05-840R21400 with Martin Marietta En- ergy Systems, Inc. We also acknowledge the support oftheNational Institute of Standards and Technology, U.S. Department of Commerce, in providing some of the facilities used in this experiment. This material is based in part upon activities supported by the National Science Foundation under Agree-ment DMR-9122444. We are grateful for the experimental help of G. D. Wignall, C. Glinka, and J. Barker. This research was also supported in part by the Whitaker Foundation and by grant DK-41678 from the National Institutes of Health. Dr. Sum P. Lee is supported in part by the Medical Research Service of the Department of Veterans Affairs.