Fig. 20.

[A]: Root mean square fluctuation (RMSF) values as a function of furin residue number over the course of the 132-ps iMD trajectory. RMSF indicates positional differences between entire structures over time and calculates individual residue flexibility. The large fluctuation of W254 is attributed to its forced (ligand induced) rotation about its chi-1 dihedral angle. It is noteworthy that 4–5 additional residues also exhibited some motions in excess of about 1.5 Å RMSF relative to their t = 0 conformations. Such motion was attributed to interaction of Mod23 with residue side chains comprising the entry channel to the furin binding pocket. [B]: B-factor coloration of residues computed over the 132-ps intMD trajectory. B-factor (also referred to as the Debye-Waller factor, temperature factor, or atomic displacement parameter) is used in protein crystallography to quantify attenuation of X-ray scattering by thermal motion and reflects residue flexibility. Furin is depicted as a residue trace with small spheres marking residue positions along the protein backbone. The magnitude of residue motion is color-keyed as follows: Yellow > > Orange > > Magenta > > Blue (frozen).