Fig. 4

Cysteine-containing dipeptide formation in the in vitro assays measured by the method of S-bimanyl derivatization developed in this study (Fig. 2). For the assays, supernatant of cell lysate from WT pQE85-BsBacD pCysHP was utilized, and the substrates were cysteine and a histidine, b serine, c threonine, d valine, e proline, f glycine, g methionine, h isoleucine, i leucine, j cysteine, k phenylalanine, or l tryptophan. Measured S-bimanyl dipeptides are indicated in the figures. The y-axis represents normalized peak area in the mass chromatogram monitoring m/z characteristic of individual target compounds, and x-axis represents reaction time of the assay; sampling time is 0, 1, 3, 5 min (see “Materials and methods”). Data values are mean ± SE (n = 3)