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. Author manuscript; available in PMC: 2013 Jan 6.
Published in final edited form as: J Mol Biol. 2011 Oct 28;415(1):102–117. doi: 10.1016/j.jmb.2011.10.040

Figure 6.

Figure 6

Interactions of AP and NPP with ground-state and transition-state analogs. The indicated distances are averages over all monomers in the asymmetric unit. (A) Overlay of structures of AP bound to inorganic phosphate (reported herein, 1.29 Å) and NPP bound to AMP (2GSU, 2.0 Å). (B) Overlay of vanadate-bound structures of AP (1B8J, 1.9 Å) and NPP (2GSO, 1.45 Å). (C) Schematic of expected protonation states in AP and NPP upon binding phosphate, AMP, and vanadate. No experimental evidence addresses the position of the proton in the NPP•AMP complex, but the proton may transfer to Thr90, analogous to a model based on isotope-edited IR studies in AP 32.