Time-resolved x-ray solution scattering from detergent solubilized visual rhodopsin

Time-resolved x-ray solution scattering (TR-XSS) studies provide experimental probes of transient conformational states in macromolecules. Difference x-ray scattering curves from integral membrane proteins are predicted to be influenced by the presence of the surrounding detergent micelle. Here, we present time-dependent x-ray solution scattering data from visual rhodopsin when solubilized in two different detergents: the nonionic surfactant n-dodecyl-β-D-maltoside and the zwitterionic detergent 3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate. Both detergents produce micelles that surround rhodopsin, yet they have different composition, density and critical micelle concentrations and yield different x-ray scattering properties. Our theoretical framework is able to fit the experimental TR-XSS data for photoactivated rhodopsin in both detergents, yielding experimental verification of how x-ray scattering contrast from the detergent molecules influences difference x-ray scattering measurements from integral membrane proteins. These results increase confidence when modeling conformational changes of integral membrane proteins from an ensemble of predicted structures.