1. Detergents – amphipathic/amphiphillic molecules that have a limited solubility and above a critical concentration form micelles (CMC). micellemonomer When micelles are present, there is always free monomer present too If detergent concentration is less than CMC, monomers are in solution If detergent concentration is above CMC, …..

2. Detergents are typically broken down into 4 classes:

4. * *

6. General Properties of Classes of Detergents for Membrane Protein Studies *SDS will help stabilize an all a-helix peptide/protein.

7. Detergent Elimination Strategies: Dialysis Dilution Size Exclusion Biobeads (hydrophobic adsorption) Membrane Protein Reconstitution Solubilizing Membranes Protein Purification Schemes

8. Features of the 4 stages:... Ratio of detergent/lipid important, [] detergent important

10. Turbidity and Light Scattering: An increase in turbidity/light scattering is an indication of a larger size particle (as long as the wavelength used is larger than the particle size). The decrease is taken as solubilization. Turbidity is often measured in simple spectrophotometer ( 300- 500nm) At solubilizing concentrations, most detergents will actually increase turbidity: shown to result from reassembly into multilammellar structures at point of solubilization.

11. Turbidity and Light Scattering: “light scattering” performed as 90o scattered light under steady state conditions using a spectrofluorometer. It is more sensitive than turbidity, can have smaller sample sizes and go to longer wavelengths. “dynamic light scattering” = “quasielastic light scattering”=photon correlation spectroscopy : the intensity of scattered light is monitored in the ms time range. The Brownian motion of the particles induces a broadening of the spectrum, in a way that is related to their size and shape. You can determine round from disk from tubes etc.

13. Entire Issue of BBA biomembranes: Volume 1508, Nov 2000

14. Effects of Salt and Urea Vesicle solubilization Salt Effects on detergent CMC

15. Studies go both ways: Solubilization of Liposomes by Detergents Removal of Detergents to Form Proteoliposomes.