Fig. 1. Rates of hydrolysis of insect peptides by neprilysin. Rates were determined using HPLC to measure the linear decline in the peptide substrate during incubation with human neprilysin, as described in Materials and methods. Values are the means ± s.e.m. of at least three determinations. A unit of activity is 1 nmole of peptide hydrolysed per ng of neprilysin.