FIGURE 3.

Binding of proCELA3B to proCPA1 (A) and proCPA2 (B). Equilibrium binding assays using purified proenzymes were carried out as described under ”Experimental Procedures.“ The free (unbound) proCPA concentrations were plotted as a function of the total proCELA3B concentration. Data points represent the average of three replicates ± S.E. Error bars may be smaller than symbol sizes. Data were fitted globally, the K_D values and the error of the fits are indicated. The catalytically inactive S217A mutant of proCELA3B was used.