Size And Shape of Detergent Micelles Determined By Small-Angle X-Ray Scattering

Journal Article · Wed Apr 29 04:00:00 EDT 2009 · J.Phys.Chem.B111:12427,2007

OSTI ID:958667

Lipfert, Jan; Columbus, Linda; Chu, Vincent B; Lesley, Scott A; Doniach, Sebastian

We present a systematic analysis of the aggregation number and shape of micelles formed by nine detergents commonly used in the study of membrane proteins. Small-angle X-ray scattering measurements are reported for glucosides with 8 and 9 alkyl carbons (OG/NG), maltosides and phosphocholines with 10 and 12 alkyl carbons (DM/DDM and FC-10/FC-12), 1,2-dihexanoyl-sn-glycero-phosphocholine (DHPC), 1-palmitoyl-2-hydroxy-sn-glycero-3-[phospho-rac-(1-glycerol)] (LPPG), and 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonate (CHAPS). The SAXS intensities are well described by two-component ellipsoid models, with a dense outer shell corresponding to the detergent head groups and a less electron dense hydrophobic core. These models provide an intermediate resolution view of micelle size and shape. In addition, we show that Guinier analysis of the forward scattering intensity can be used to obtain an independent and model-free measurement of the micelle aggregation number and radius of gyration. This approach has the advantage of being easily generalizable to protein-detergent complexes, where simple geometric models are inapplicable. Furthermore, we have discovered that the position of the second maximum in the scattering intensity provides a direct measurement of the characteristic head group-head group spacing across the micelle core. Our results for the micellar aggregation numbers and dimensions agree favorably with literature values as far as they are available. We de novo determine the shape of FC-10, FC-12, DM, LPPG, and CHAPS micelles and the aggregation numbers of FC-10 and OG to be ca. 50 and 250, respectively. Combined, these data provide a comprehensive view of the determinants of micelle formation and serve as a starting point to correlate detergent properties with detergent-protein interactions.

• Research Organization: Stanford Linear Accelerator Center (SLAC)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC02-76SF00515
• OSTI ID: 958667
• Report Number(s): SLAC-REPRINT-2009-006
• Journal Information: J.Phys.Chem.B111:12427,2007, Journal Name: J.Phys.Chem.B111:12427,2007 Journal Issue: 43 Vol. 111; ISSN 1089-5647; ISSN JPCBFK
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CHEM
PHYS
DETERGENTS
DIMENSIONS
ELECTRONS
MEMBRANE PROTEINS
RESOLUTION
SCATTERING
SHAPE
SULFONATES