Figure 3.

Sequential conformational changes of vanadyl-nucleotides bound to specific F₁-ATPase catalytic sites demonstrate the F₁ binding-change mechanism. (A) Equatorial ligands determine ⁵¹V-hyperfine Parameters of VO²⁺. EPR spectra of VO²⁺ with water (top) or hydroxyl groups (bottom) as equatorial ligands. The parallel transitions (−7/2_||, −5/2_||, +3/2_||, +5/2_||, and + 7/2_||) that are not superimposed with perpendicular transitions are identified. Inset: dependence of the −5/2_|| transition on the type of equatorial ligands. (B) The −5/2_|| transition(s) of VO²⁺ bound to SoF₁ as: (a) VO²⁺–ATP at latent Site-2, (b) VO²⁺–ADP bound to latent Site-3, (c) VO²⁺–ADP bound to activated Site-3, (d) VO²⁺–ATP bound to activated site 3; and (e) VO²⁺–ATP bound to Site 1 using SoF₁–ε. This figure was modified from Frasch (2000a,b) with permission of the publisher.