Figure 2: The PceA substrate-binding pocket.
From: Cobamide-mediated enzymatic reductive dehalogenation via long-range electron transfer
(a) Positioning of 2,4,6-TBP in the active site as revealed by structural analysis. Shown is a cross-section through the binding pocket viewed from the substrate channel (Tyr102) (upper figure) or viewed from Tyr246 with the substrate channel on the right (lower figure). The Co-water/hydroxyl ligand and further water molecules are shown as blue spheres. (b) Distances between 2,4,6-TBP and Tyr102, Tyr246, Tyr382 and cobalt. A single hydrogen bond may be formed to the phenolic hydroxyl of Tyr246. Probability of a halogen substituent at different C-atoms provides a tentative model for the binding of other monoaromatic substrates. Besides the allowed substitution positions shown, the Tyr102-oriented position is possibly allowed after a small rotation of the substrate. A substituent at the Tyr382-oriented position is not possible due to bulky obstruction.
