Fig. 2

rhCTSK can cleave and activate rhproMMP-9 at acidic pH. a rhproMMP-9 (5.0 ng) was incubated with rhCTSK (0.5 ng) at pH 5.0 for the duration indicated, and then analyzed via gelatin zymography. b Quantification of active MMP-9 using the zymography data shown in a. Y-axis is the ratio between active- and proMMP-9, measured from the relative light intensity. Data is presented as mean ± SD, n = 3. c Zymograph of solutions of rhproMMP-9 (5.0 ng) incubated for 1 h, at 37°C with or without rhCTSK (0.5 ng) at pH 7.5 or pH 5.0. d Quantification of zymography bands shown in c. Y-axis is the ratio between active- and proMMP-9, measured from the relative light intensity of the bands normalized to the control condition without rhCTSK. Data is presented as the mean ± SD, n = 8. e rhproMMP-9 (5.0 ng) was first incubated for 1 h at 37°C at pH 5.0 with or without rhCTSK (5.0 ng), and then pH was adjusted to 8.0 and incubated for an additional 2 h at 37°C with or without APMA (final concentration 1.5 mM), and then analyzed via gelatin zymography. f Quantification of MMP-9 activity using a fluorescently quenched substrate for MMP-9 (Mca-RPPGFSAFK(Dnp)). Data is presented as the mean ± SD, n = 3. *P < 0.05 and **P < 0.01.