Figure 6. Contribution of the first twenty PCA eigenvectors to the overall closing motion of the PSI.

The contribution of the first 20 PCA eigenvectors to the closing motion of the PSI at active (A) and inactive (B) pH are presented. The first eigenvectors contribute 78.8% and 74.2% of the overall motions for the pH 4.5 and pH 7.4 simulations, respectively, and correspond to the collapse of helices α1/α2 onto helices α3/α4.