Enzymatic conformational fluctuations along the reaction coordinate of cytidine deaminase.

Analysis of the crystal structures for cytidine deaminase complexed with substrate analog 3-deazacytidine, transition-state analog zebularine 3,4-hydrate, and product uridine establishes significant changes in the magnitude of atomic-scale fluctuations along the (approximate) reaction coordinate of this enzyme. Differences in fluctuations between the substrate analog complex, transition-state analog complex, and product complex are monitored via changes in corresponding crystallographic temperature factors. Previously, we reported that active-site conformational disorder is substantially reduced in the transition-state complex relative to the two ground-state complexes.