Summary of experimental results using the schematic representation of the α3β3γ complex viewed from the Fo side. (a) Schematic representation of the crystal structure. The scheme employed by Abrahams et al. 11 is used for the naming of the α and β subunits. A yellow line represents that the packing in the two adjacent subunits is especially tight. 37 Three circular arcs denote sub-complexes I (black), II (blue), and III (red), respectively. The definition of each sub-complex is described in “Decomposition of α3β3γ complex into components.” The other figures represent (b) the overall configuration after the first 40° rotation of the γ subunit and (c) that after the second 80° rotation of the γ subunit. Primes are added to the subunits in (b) because their conformations should be different from those in (a). The arrow at the center of the γ subunit is defined in our previous paper. 23 Although ATP is bound to each of the three α subunits, it is not shown here.
Changes in the system free energy during the 120° rotation of the γ subunit. “ATP hydrolysis” means the hydrolysis within βDP. “Configurational (structural) reorganization” means that of the α3β3γ complex.
Schematic representation of the crystal structures of yeast F1-ATPase. 13 Configurations (a) and (b) correspond to yF1 II and I, respectively. Relative to (a), the γ subunit of (b) rotates by 16° in the counterclockwise direction when it is viewed from the FO side. Pi is bound to βE in (a) while nothing is bound to that in (b), implying that Pi triggers the 16° rotation. Although ATP is bound to each of the three α subunits, it is not shown here.
Hydration free energy μ, entropy S, and energy U for a spherical solute with diameter 0.28 nm. 27 e is the elementary electric charge.
Hydration entropy S/k B and its change during the 16° rotation for each sub-complex defined in “Model and Theory.” “Before” and “After” correspond to yF1 II (before the rotation) and I (after the rotation), respectively. The column of “Change” shows the change in S/k B caused by the rotation.
Change in the water-entropy gain upon the formation of each subunit pair during the 16° rotation (in k B). The water-entropy gain is given as the difference between the hydration entropy of a subunit pair and the sum of the hydration entropies of separate subunits forming the pair (see Eq. (1) ).
Change in the hydration entropy of each subunit during the 16° rotation (in k B).
Hydration entropy S/k B and its change during the 16° rotation for each sub-complex without the γ subunit. “Before” and “After” correspond to yF1 II (before the rotation) and I (after the rotation), respectively. The column of “Change” shows the change in S/k B caused by the rotation.
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