FIGURE 6.

Quantitative analysis of nukacin ISK-1 production (black bars) and peptidase activity (white bars) with wild-type NukT and NukT(N106D). Nukacin ISK-1 production was assessed by measuring antibacterial activity (arbitrary units (AU)/ml) against L. sakei as an indicator strain. Peptidase activity was determined by the remaining substrates (modified His-NukA) in the reaction mixture of the in vitro assay, followed by Western blotting using anti-His antibody. The signals of the remaining substrates were quantified by Multi Gauge software. Substrate consumption by wild-type NukT was taken as 100%. This assay was performed in duplicate, and the average values are shown with error bars.