Figure 3.

Proposed hydrogen bond network for AMP deaminase at the transition state. (a) Model depicting one hydron “in flight” linked to the Zn²⁺-bound water (from water to Asp707), applicable to AMP as substrate. (b) Model depicting two hydrons “in flight” linked to the Zn²⁺-bound water (from water to the leaving ammonia and from His652 to Asp707), applicable to 2′dAMP and 8-bromo-AMP as substrates. Figure was adapted from Merkler and Schramm [31].