Activity of 1.5 mg AAP/LDH samples, treated with various concentrations of salt, as a function of the absorbance of 4-nitroaniline produced in a 4 minute reaction of each sample with 100 μM LPNA, versus the concentration of NaCl solution used to treat the particular sample of AAP/LDH. Reactions were carried out in 10 mM tricine buffer, 0.1mM ZnSO4, pH 8.0.