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. Author manuscript; available in PMC: 2017 Aug 5.
Published in final edited form as: J Am Chem Soc. 2017 May 12;139(26):8837–8845. doi: 10.1021/jacs.7b01594

Fig. 4. Structural differences between the filters with and without ions in the closed and open states.

Fig. 4

Illustration defining φ and ψ angles for the states in which a K+ ion is (A) bound and (B) not bound at the S1 site taken from representative snapshots of the 2128 frames sampled from the 532 ns trajectory. Plot of the φ and ψ angles when (C) an ion is bound and when (D) an ion is not bound at the S1 binding site, showing that the filter fluctuates less when an ion is present. Dihedral angles are shown for the two major conformations of the (red) open-constricted and (blue) closed-constricted states. The φ angle is defined by the Gly77 carbonyl carbon, Tyr78 amide nitrogen, Tyr78 Cα, and the Tyr78 carbonyl carbon. The ψ angle is defined by the Gly77 amide nitrogen, Gly77 Cα, Gly77 carbonyl carbon and Tyr78 amide nitrogen.