Figure 8

Rearrangement of contacts explains the changes in flexibility of catB View of the contacts established under the distinct pH conditions. In apo catB in acidic conditions two stable interactions are estabilished between Q23 and S220. Due to deprotonation of E36 in alkaline conditions, the pattern of interactions is changed and a new interaction is formed (E36 – S220). However, there is a loss of 1 hydrogen bond between !36 and S220 in this condition. Residues involved in the rearrangement are represented in stick representation and numbered. The conformation of D22 is represented since this residue is crucial in stabilization of the occluding loop.. Domains are colored blue and red (L and R, respectively). Hydrogen bonds are represented by dashed lines.