Figure 5.

Effect of metal concentration on arginase activity in E. coli (pBS-barocF) whole cells. Cells were grown in the absence or presence of various concentrations of metal (CoCl₂, MnSO₄, or NiCl₂). No effect on growth was observed at the concentrations used. Whole cells were harvested and assayed directly without heat treatment (ice, 30 min) at pH 6.0 (A) or 9.0 (B) using MES- or Tris-arginine buffer, respectively. Data shown is represented as the fold increase over the no metal control. Under these conditions, E. coli DH5α(pBS) showed a background of ~1000 pmol L-orn/min/mg protein [U]. Before fold-increases were calculated, 1000 U was subtracted from each E. coli DH5α (pBS-barocF) data point.