FIG. 3.

Correlation of nitrogenase activity with modification of Fe protein. K. pneumoniae cultures were derepressed for nitrogenase activity. Inactivation of nitrogenase was initiated by addition of 0.5 mM ammonium acetate. (A) Traces of nitrogenase activity (■) and modification of Fe protein (□) in UN5482 (draTGB transformant, wild-type background) are recorded. (B) Corresponding immunoblot of nitrogenase Fe protein from UN5482. The upper band (U) corresponds to the ADP-ribosylated form of Fe protein. The lower band (L) represents unmodified Fe protein. (C) Traces of nitrogenase activity (⧫) and modification of Fe protein (◊) in UN5483 (draTG′ transformant, wild-type background). (D) Corresponding immunoblot of nitrogenase Fe protein from UN5483. The positions of the upper (U) and lower (L) bands are indicated.