Extended Data Figure 9: HPLC-MS analysis of P450-catalysed peptide bicyclization.
From: X-domain of peptide synthetases recruits oxygenases crucial for glycopeptide biosynthesis
a–d, Representative HPLC-MS chromatograms of coupled in vitro OxyBtei plus OxyAtei (a), OxyCtei (b), or OxyAtei/OxyCtei (c) turnover reactions on heptapeptide Tei7(Hpg3,7) bound to GB1–PCP7–X (a, left, b, c) and GB1–PCP7 (a, right); or OxyBtei alone with hexapeptide Tei6(Hpg3) bound to MBP–PCP6 (d). Occurrence of ions corresponding to the singly charged, linear peptide (hydrolysed m/z 1,088, methylhydrazide m/z 1,116 (a–c); hydrolysed m/z 939, methylhydrazide m/z 967 (d)), crosslinked monocyclic product (hydrolysed 1,086 m/z, methylhydrazide 1,114 m/z (a–c); hydrolysed m/z 937, methylhydrazide m/z 965 (d)), crosslinked bicyclic product (hydrolysed m/z 1,084, methylhydrazide m/z 1,112) and the crosslinked tricyclic product (hydrolysed m/z 1,082, methylhydrazide m/z 1,110) was recorded using SIM in negative mode. The origins of the multiple peaks observed for each mass are described in Extended Data Fig. 7.
