Fig 4. PO activity detected by the DCPIP assay method on mitochondrial fractions of U87 cells transiently transfected with wild-type or L441P PO and collected 48 h after transfection.

Absorbance changes were corrected for the value detected in untransfected, control U87 cells. A) Activity measurements are for the entire mitochondrial protein content. B) Activity measurements were normalized to the amount of PO present in the mitochondrial fraction as assessed by Western blot analysis. The assays were performed using 100 or 200 mM L-Pro as substrate. Black bars: wild-type PO; white bars: L441P PO. The value is expressed as the mean ± standard error (n = 3). ** p ≤ 0.0005; * p ≤ 0.005.