Biophysical Journal 89 6

Cover picture: Time-resolved fluorescence anisotropy decay experiments on a dye attached to the AB-loop of bacteriorhodopsin probe local protein dynamics and steric restrictions. Molecular dynamics simulations of these experiments agree with the measured decay curves and provide structural and time-resolved interpretations at the atomic level. The picture shows the orientation distribution of the dye's transition dipole moment, as calculated from the simulations. The two directional histograms (color-coded) refer to two conformational states revealed by the simulations. Accordingly, straightforward application of the widely used wobbling-in-a-cone model would overestimate the loop flexibility. See the article by Schroder et al. on page 3757.