Fig. 2

Optimization of a quantitative PR3/PRTN3 activity assay for urine. a Urine from a normal healthy donor was either untreated (X) or passed through a Zeba plate (white-up pointing triangle) and after which 4 nM of purified proteinase 3 was added and assayed. Note increased slope and linearity of activity in the Zeba passaged urine. b The activities of the indicated amounts of purified PR3/PRTN3 were added to an in inactive urine and assayed: (1) 8 nM, (2) 4 nM, (3) 2 nM, (4) 1 nM, (5) 0.5 nM, (6) 0.25 nM, (8) 0.125 nM, (8) 0.0625 nM. c The effect of repeated freezing and thawing of purified PR3/PRTN3 in urine on enzyme activity after 1 freeze/thaw (X) or 7 freeze/thaw cycles (white-up pointing triangle)