Fig. 2.

Heme access channel of (A) MroUPO (short UPO family) and (B) AaeUPO (long UPO family). Glutamic acid from the acid base pair is depicted in blue (Glu157 in MroUPO and Glu196 in AaeUPO) and charge stabiliser amino acid is colored in yellow (His86 in MroUPO and Arg189 in AaeUPO). Heme access channel lining amino acids are represented in orange (hydrophobic aliphatic in MroUPO) and in pink (hydrophobic aromatic in AaeUPO). The models were visualised with Pymol (http://pymol.org) using the crystal structure of MroUPO at a resolution of 1.83 Å (PDB ID: 5FUJ) and AaeUPO at a resolution of 2.19 Å (PDB ID: 2YOR). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)