3.4 Normal Rotation Under Solution Condition …
49
subunit to rotate in the normal direction in response to the packing structure of the
α 3 β 3 complex; however, such narrow interfaces weakens the entropic force by water,
causing the slower and more irregular motion of the γ subunit (see Sect. 3.8.4 also).
3.4.4 Change in System Free Energy During a Single
Rotation
After the 120° rotation of the γ subunit, the α 3 β 3 γ complex returns to the same
state, but one ATP molecule is decomposed into ADP and Pi by the hydrolysis
reaction (ATP + H 2 O→ADP + Pi). As depicted in Fig. 3.18, the dissociation of
Pi and the ATP hydrolysis occur in state change (a)→(b), and the ATP binding and
the dissociation of ADP occur in state change (b)→(c). The structure of the α 3 β 3 γ
complex is reorganized in each of state changes (a)→(b) and (b)→(c) to retain the
Fig. 3.18 Decrease of system free energy during a single rotation of γ subunit (i.e., one ATP
hydrolysis cycle)
49
subunit to rotate in the normal direction in response to the packing structure of the
α 3 β 3 complex; however, such narrow interfaces weakens the entropic force by water,
causing the slower and more irregular motion of the γ subunit (see Sect. 3.8.4 also).
3.4.4 Change in System Free Energy During a Single
Rotation
After the 120° rotation of the γ subunit, the α 3 β 3 γ complex returns to the same
state, but one ATP molecule is decomposed into ADP and Pi by the hydrolysis
reaction (ATP + H 2 O→ADP + Pi). As depicted in Fig. 3.18, the dissociation of
Pi and the ATP hydrolysis occur in state change (a)→(b), and the ATP binding and
the dissociation of ADP occur in state change (b)→(c). The structure of the α 3 β 3 γ
complex is reorganized in each of state changes (a)→(b) and (b)→(c) to retain the
Fig. 3.18 Decrease of system free energy during a single rotation of γ subunit (i.e., one ATP
hydrolysis cycle)