Figure 5

Movement of the C1' of the ribose ring throughout catalysis by pPNP. Top figure shows two perpendicular views of an overlay of the ribose and surrounding atoms in Pf PNP-inosine/Pf PNP-SO₄ (Michaelis complex, green), Pf PNP-ImmH (transition state, purple) and Pf PNP-hypoxanthine-ribose-AsO₄ complex (post-transition state, yellow) structures. Bottom panel show the distances between C1'-N9 and C1'-nucleophilic oxygen when comparing ligands in different states with the sum of the reaction coordinate distance (Σ) shown. The numbers in brackets are the values proposed by KIE calculations between the Michaelis complex and transition state [17] or those observed in bPNP crystal structures representing the transition state and post-transition state [5]. This figure is similar to those compiled previously for other PNP combinations such as in [5, 26, 27].