Heme proteins, especially the truncated globin GlbN in Mtb possess oxygen-dependent nitric oxide dioxygenase activity, where the heme that is oxidized to ferriheme in the process will need to be reduced in a second step to activate the protein again. The responsible heme protein reductase is unknown (Ouellet et al. 2002, Pathania et al. 2002).
nitric oxide dioxygenase activity of GlbN:Heme dimer [cytosol]