Cleavage of protein substrates by PSA.

<p>(A) Characterization of the proteolytic activity of PSA (0.2 µM) during 22 h incubation towards different protein substrates (1 µM each, except 0.5 µM semenogelin I) by SDS-PAGE and silver staining. Approximate molecular weights of the proteins are: PSA (28 kDa), semenogelin I (50 kDa), semenogelin II (63 kDa), fibronectin (220 kDa), galectin-3 (26 kDa), IGFBP-3 (30 kDa) and nidogen-1 (130 kDa). The lanes in which ∼50% of the proteins were cleaved are bordered. (B) 1 µM MMP-3 (22 kDa), but not PSA, cleaved 1 µM plasminogen (88 kDa). Also 0.5 M fibronectin was incubated with 1 µM PSA as a control (SDS-PAGE with silver staining).