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.