Exponentially growing E. coli cells were exposed to pure NO gas at a rate of ∼ 100 nM per second for 10 min anaerobically, followed by purge with pure argon gas to remove residual NO in cell culture. The NO-exposed E. coli cells were returned to either A) anaerobic or B) aerobic growth conditions in minimal medium containing 0.2% glucose. Circles: untreated E. coli cells. Triangles: the NO-exposed E. coli cells. C), the NO-exposed E. coli cells were returned to anaerobic growth conditions in minimal medium containing 0.2% glucose supplemented with three branched-chain amino acids (leucine, isoleucine, valine) (filled triangles), three non-branched-chain amino acids (glycine, alanine and lysine) (open diamonds) or an equal volume of de-gassed water (open circles) anaerobically. The final concentration for each amino acid in the minimal medium was 100 μg/ml. The cell growth was measured as described in the Experimental Procedures. The data are the representatives of three independent experiments.