Figure 5.

(a) Structural view of the hydrogen bond formed at the “tyrosine corner” in C-td. (b) and (c) Number of hydrogen bonds at the “tyrosine corner” during the unfolding simulation for both the wild-type and quadruple KN mutant. (d) Structural view of the Tyr-Trp-Tyr sandwich-like cluster. (e) and (f) sidechain-sidechain distance between the Trp/KN and Tyr around the mutation site in N-td and C-td, respectively. The mutation destabilized the ‘‘tyrosine corner’’ and broke the Tyr-Trp-Tyr sandwich-like cluster.