Figure 3.

Serine proteinase activity in SF from PsA, RA and OA patients. Serine proteinase activity using fluorogenic substrates for trypsin-like proteinases with a preference for arginine (VPR) or lysine (VLK) (A) and chymotrypsin-like proteinases (B) is shown. Fluorescence release was monitored for 20 min of a kinetic cycle and the slope of the resulting curve was extrapolated relative to a standard curve of fluorescence release by known concentrations of either trypsin or chymotrypsin and normalized to the total protein concentration of the sample. Representative standard curves are shown in (C) for each substrate. Groups were compared using the Kruskal-Wallis test with Dunn’s multiple comparisons test. Asterisks are used to indicate significant differences between groups, where **p<0.01 and ***p<0.001.