Figure 1. Hydrolysis of the fluorogenic peptides 1 and 2 by ZapA. Solutions of peptide 1 (Abz-R-P-P-G-F-S-P-F-R-EDDnp) and of peptide 2 (Abz-G-G-F-L-R-R-Q-EDDnp) were incubated with 2.8 pM purified native ZapA in 50 mM Tris-HCl and 2 mM CaCl₂, pH 8.0, at 37ºC for 3 h. The hydrolysis products were analyzed by HPLC as described in Material and Methods. The chromatograms in panels A and B show the elution profiles of the fragments generated by the incubation of peptide 1 and peptide 2 with ZapA, respectively. Dashed lines indicate fluorescence and continuous lines show the absorbance at 214 nm. Bk = bradykinin; Dyn = dynorphin.