Protonation state of F420H2 in the prodrug-activating deazaflavin dependent nitroreductase (Ddn) from Mycobacterium tuberculosis.

The protonation state of the deazaflavin dependent nitroreductase (Ddn) enzyme bound cofactor F-420 was investigated using UV-visible spectroscopy and computational simulations. The reduced cofactor F420H2 was determined to be present in its deprotonated state in the holoenzyme form. The mechanistic implications of these findings are discussed.