Figure 7.

CC9 Inhibits Apoplastic Cys Proteases.

(A) Apoplastic fluid from maize seedling leaves 2 d after treatment with 2 mM SA, separated by anion-exchange chromatography. Top panel shows elution conditions and a typical profile of eluted proteins. Activity of proteases was tested in the presence (open symbols) and absence (closed symbols) of 5 μM E-64 using Z-Phe-Arg-AMC as substrate. Error bars represent se.

(B) Protease activity was determined after incubation with 0.5 μM CC9^ia (open symbols) or 0.5 μM CC9 (closed symbols) using Z-Phe-Arg-AMC as substrate. The dashed line shows the protease activity without inhibitor (see [A]).

(C) Apoplastic fluid (peak fraction 19.5 mL of [A]) was preincubated with different concentrations of CC9 (white bars) or CC9^ia (black bars). The protease activity of the untreated apoplastic fluid fraction was set to 100%. The dotted lines represent se of the untreated sample. Error bars represent se. Experiments were done in three biological replicates.