Fig. 5.
Small internal friction in the folding of the L24A FF domain. (A) Structures of the native (27) and intermediate states (PDB ID: 2L9V) (27) of the four-helix bundle L24A FF domain, the fractional populations of N and I, and kIN, kNI rate constants, 30 °C, as measured in the present study. Helix boundaries are depicted according to TALOS+ (37), as described previously (27), whereas MOLMOL (50) predicts slightly different boundaries. Y49, which moves out of the protein core during folding, is shown explicitly. (B) Variation in intermediate- and native-state lifetimes as a function of viscosity in BSA-containing samples. Internal friction values obtained from fits to Eq. 3 (solid lines) are indicated.