Fig. 2

Serin protease activity of EcN Sat. a Concentrated culture supernatants (200 μg total protein) from the indicated E. coli strains were incubated with 1 mM methoxysuccynil-Ala-Ala-Pro-Val p-nitroanilide at 37 °C for 18 h. Activity values, expressed as pmoles/μg protein at18 h, were the mean ± SE of three independent assays. Asterisks indicate values significantly different from that of the knockout mutant EcNsat::cm (^* P < 0.05; ^** P = 0.000). Expression of Sat analysed by Western blot in each culture supernatant is shown in the upper panel. b Spectrin degradation by EcN Sat. Spectrin (4 μg) was incubated with the indicated culture supernatants or left untretaed. Reaction products were separated by SDS-6 % PAGE and stained by Commassie Blue. M, molecular mass marker