To maintain symmetry, this step was assigned to the dissociation/association of ADP, which is the last hydrolysis product to leave the NBD

In our adaptation of the design (shaded cycle, Figure 2), the two equal varieties of the enzyme, E and F, correspond to states of the enzyme with similar energetic and/or conformational states that vary only in the hydrolytic houses of their individual NBDs. This notation is necessary to distinguish ATP ATP among the two-nucleotide species, EATP =FATP , in accordance to their NBD hydrolytic action, i.e. the E-type is able of hydrolyzing only the ATP molecule bound at NBD1 (but not at NBD2), and vice versa for the F-type, as a result shifting the enzyme symmetrically amongst each states. Two distinct models can account for the E/F kinds in equally it is needed to include ATP binding at every single NBD of the bare enzyme as a initial action (priming reaction) to get the preliminary intermediates of the cycle: (i) starting from the exact same conformer of the enzyme, P, recruitment of the NBDs to the nucleotide-sure state occurs randomly, with the overall reaction E ADP