Figure 8.

HRMS/MS fragmentation of the Copro (A) and harderoporphyrin (B). A, analytical standard of Copro was subjected to HPLC–HRMS/MS analysis to provide background data for identification of the unknown tetrapyrrole found in ΔhemJ/hemG cells. It provided molecular ion at m/z 655 when subjected to HPLC–HRMS/MS, and its subsequent fragmentation led to formation of ions corresponding to four consecutive losses of propionic radical. B, harderoporphyrin was isolated from ΔhemJ/hemG cells grown without glucose. The HPLC–HRMS/MS analysis provided molecular ion at m/z 609 with only three consecutive losses detected in its MS/MS spectrum. The fourth propionic group is substituted by a vinyl group as inferred from differences between Copro and harderoporphyrin m/z values.