Figure 2.

(A) Δ2-22AP activity during growth (time zero) and in stationary phase (2 days). AP activity measured in aerobically grown cells was normalized to total cell mass (OD₆₀₀) before (open bars) and after an osmotic shock treatment (hatched bars). Activity was measured also in cells grown and starved anaerobically (shaded bars) and aerobically in the presence of 4 mm DTT (black bars). (B) Wild-type AP activity before (open bars) and after an osmotic shock (hatched bars). (C) Determination of Δ2-22AP activity after separation of crude extract by gel filtration on Sephacryl HR 100. The relative levels of Δ2-22AP in the eluted fractions were determined by Western blotting using polyclonal antibodies against AP and quantification of Δ2-22AP bands was performed electronically using the ImageQuant (Molecular Dynamics) software. (D) Effect of DTT (4 mm) on the in vitro Δ2-22 AP activity. See text for details. The analysis was repeated three times to confirm reproducibility. Representative results are presented and the standard deviation was always <7% in the measurements of AP activity.