Figure 1.

SNO and NO metabolism in E. coli. (A) E. coli release NO from S-nitrosothiols. S-nitrosocysteine (0.1 mM) was added to growth medium (broken line) or a suspension of E. coli (A ₆₀₀ = 1; 2 × 10⁹ cfu/ml) in growth medium (solid line), and NO release was measured with an NO electrode. (B) E. coli consume NO in both a constitutive and an inducible manner. A saturated solution of NO was added to growth medium (dotted line), to a suspension of E. coli that had received no treatment (dashed line), or to E. coli pretreated with 0.2 mM SNO-Cys for 90 min (solid line). (C) E. coli contain SNO-lyase activities. A bacterial extract was separated by anion-exchange chromatography, and the column fractions were assayed for the accumulation of nitrite from 0.5 mM SNO-Cys. (D) E. coli contain an inducible NO-metabolizing heme protein. Absorption spectra of column fractions from untreated (dashed line) or SNO-Cys pretreated cells (solid line), which contain the inducible NADH-dependent NO-metabolizing activity.