Figure 3.

MALDI-TOF MS and MS/MS analysis of [d₅]-DA-LppK58A-strep tag purified from strain TXM1111 and KA775. Trypsinized Lpp lipopeptides purified from strains grown with [d₅]-octanoate were extracted from TXM1111 (A) or the control strain KA775 (D) and analyzed by MALDI-TOF MS. B, MS/MS spectra of the 1167.8 u parent ion was used to elucidate the N-terminal structure of Lpp as [d₅]-DA-LppK58A with two labeled acyl chains (C). MS/MS spectra of the 1157.8 u parent ion (E) confirmed a free α-amino N terminus in DA-LppK58A (F). Calculated peak assignments are detailed in Table 1.