Finally, the loop structures share some similarities with α-helix and exhibit important differences across morphologies. In filaments and weakly bundled networks, the loops have features similar to those of the α-helix, with 1 ps dynamics and 0.2 offset. In contrast, the CLS curve in strongly bundled networks has a fast decay within 0.3 ps and an offset afterwards (Figure ), similar to the results of β -sheet. Thus, loop structures are mostly exposed to free solvents in the filament and weakly bundled network but are almost constrained in "buried" positions with little solvent exposure in the strongly bundled network. The diverse features of loops from filaments to strongly bundled networks seem to indicate the important role of the disordered backbone in the physical and biochemical properties of actin networks.