Scavenging of reactive nitrogen species by mycobacterial truncated hemoglobins.

Tuberculosis and leprosy are among the most challenging infectious threats to human health. The ability of mycobacteria to persist in vivo in the presence of reactive nitrogen and oxygen species implies the presence in these bacteria of effective detoxification (pseudoenzymatic) systems. Mycobacterium tuberculosis and Mycobacterium leprae truncated hemoglobins (trHbs) belonging to group I (or N; trHbN) and group II (or O; trHbO) have recently been implicated in the scavenging of nitrogen monoxide (*NO) and peroxynitrite (ONOO-/HOONO). Furthermore, M. leprae trHbO was found to act as an efficient scavenger of the strong oxidant trioxocarbonate(*1-) (CO3*-) following the reaction of peroxynitrite with carbon dioxide (CO2). Here, mechanisms for scavenging of reactive nitrogen species by mycobacterial trHbs are reviewed, and detailed protocols for assessing pseudoenzymatic kinetics are provided.