Figure 4

Characteristics of arginase extracts from E. coli DH5α expressing the H. pylori or B. anthracis enzymes or from native organisms. Extracts were prepared from E. coli carrying H. pylori (pBS-rocF) or B. anthracis rocF (pBS-barocF) and grown in L broth at 37°C with aeration (A) or from 24 hour cultures of B. anthracis and H. pylori grown on CBA at 37°C in 10% CO₂, 5% O₂ (B). Extracts were heat-activated for 30 minutes at 50–55°C in the presence of ddH₂O (no metal control), 5 mM CoCl₂, MnSO₄, or NiCl₂ and assayed at pH 6.0 or 9.0 in MES-buffered arginine or Tris-buffered arginine, respectively (A) or at pH 6.3 or pH 9.0 in BTP-buffered arginine (B). Arginase activity data are the mean arginase activity ± standard deviation of one representative of at least two experiments (independently prepared extracts) conducted in triplicate. Under these conditions, E. coli DH5α(pBS) showed a background of ~1000 pmol L-orn/min/mg protein [U]. Lack of error bars on some bars indicates that the standard deviation was minimal and did not appear on the graph. NM, no metal.