FIGURE 5.

Limited proteolysis of wild type phosphomannomutase2 with trypsin monitored by assaying residual mutase activity. Purified wild type phosphomannomutase2 (1.4 mg/ml in 20 mm Hepes, pH 7.5 containing 150 mm NaCl and 1 mm MgCl₂) was incubated at 37 °C with (or without) trypsin (protease:enzyme ratio, 1:20) in the presence of 0.5 mm Glc-1,6-P₂ (A) or 0.5 mm Glc-1-P, 0.5 mm vanadate, or 0.5 mm Glc-1-P plus 0.5 mm vanadate (B). Residual phosphomannomutase activity is reported as a percentage with activity at time 0 defined as 100%. The protective effect of ligands increases as negative charges are added.