FIGURE 2.

ProGrB convertase assay. The activation of proGrB following treatment with CatC was assessed at 37 °C using a quenched fluorescence substrate, aminobenzoyl-IEPDSSMESK-dinitrophenyl. 2-Fold serial dilutions of CatC (20–2.5 pmol) were used to activate 20 pmol of proGrB. A, following a 1-h incubation at pH 5.5, the pH was adjusted to pH 7.4, substrate was added, and the resultant GrB activity was assayed. B, the stability and maximal activation of 20 pmol proGrB was assessed following treatment with 20 pmol CatC overnight (16 h) at pH 5.5. Data shown are representative of three experiments.