Figure 3.

Paratope states in solution of the mutant antibody Fab, characterized by the free energy surface, the respective Markov-state model and the relative V_H–V_L interdomain orientations. Panel (A) shows the free energy surface of the whole paratope based on the backbone torsions of all CDR loops. Both the human germline IGHV1-69/IGKV1-39 antibody ( Figure 2 ) and the mutant are projected into the same coordinate system. The gray dot represents the starting structure (PDB accession code: 5I15). Panel (B) illustrates the Markov-state model including the respective state probabilities. The transitions between different paratope states in solution occur in the micro-to-millisecond timescale and are represented by the thickness of the arrows. The macrostate arrangement corresponds to the free energy surface in panel (A). Panel (C) depicts the relative V_H–V_L interdomain orientations of the individual macrostates color-coded according to panel (B).