Figure 5: Complete kinetic scheme of M-PPase catalytic cycle.
(a–g) All the proposed conformational states of the M-PPase catalytic cycle are shown in order, including the transition state for pumping (d) and a ‘relaxed product’ state (f) analogous to yeast pyrophosphatase46. The structures used in the manuscript are shown, with the new structures marked in red; for the rest, the PDB code is shown. For clarity, only key helices involved in formation of the hydrolytic centre and ion channel are displayed. Aspartate and lysine residues are shown in red and blue respectively and labelled on state (a). Changes to helix position and rotation are denoted with arrows and by changes in the shading of the helices. The pumped ion (Na+/H+) is represented as a blue sphere in states (b–d) and as a large blue sphere in state (a) to denote the unknown position of the pumped ion in the channel of the resting state. The nucleophilic water is represented as a red sphere in states (b–d).
