Tissue tpa activity assay kit

The commercially available Tissue tPA Activity Assay Kit (Abcam, ab108905) was used to assess whether PAP-1 affects the ability of human tPA to cleave its substrate plasminogen (Lapchak and Boitano, 2014 (link); Lapchak et al., 2017 (link)). All reactions were run in optically clear flat-bottom 96-well plates (Corning, Catalog #3904). Human plasminogen activator inhibitor-1 (PAI-1, Sigma-Aldrich CC4075) was used as a positive control. Human plasminogen, the chromogenic plasmin substrate, and human tPA were included in the Tissue tPA Activity Assay Kit (Abcam, ab108905). PBS with 10% human serum was used as the assay medium; PAP-1 was added at 500 nM and 5 μM with a final DMSO concentration of 0.1%. The reactions were pre-incubated at 37°C for 5 min prior to addition of the chromogenic substrate and placed into a SpectraMax M5 spectrophotometer heated to 37°C. Absorbances at 405 nm were measured every 30 s for 30 min.