Figure 3.

Predominant secondary structures adopted by each linker residue when the linker is part of ADP-bound DnaK. A, the population is given as a fraction of the configurations sampled by MD. Extended structure is defined by ϕ dihedral angles between −200° (160°) and 25° and ψ dihedral angles between 50 and −140° (220°). Helical structure is characterized by ϕ dihedral angles between −110 and 25° and ψ angles between −125 and 85°. Lys³⁸⁷ populates two substates. One (Helical) has canonical ϕ, ψ values, and the other (Helical′) is distorted with a ϕ angle between −180 and −110°. Left-handed helix conformations are defined by ϕ dihedral angles between 25 and 160° and ψ dihedral angles between −60 and 100°. Dihedral angles not within the ranges described above are considered “other”. These other states are included in the total population count. B, ΔδCα − ΔδCβ secondary chemical shifts (23) from residue 384 to 395 in the two-domain construct, DnaK(1–552), in the ADP-bound state. Positive values indicate α-helical propensity, and negative values indicate β-structure propensity. Values greater than 2 ppm or less than −2 ppm suggest fully formed secondary structure, whereas smaller deviations often indicate partial secondary structure propensities.