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Fig. 4. Hemosome composition as determined by high performance liquid
chromatography (HPLC) and electrospray-ionisation mass spectrometry (ESI-MS).
(A) Transmission electron microscopy of hemosome cores after isolation through
a Percoll gradient and washing with deionised water. Scale bar, 1.0 µm. (B)
Reverse-phase HPLC fractionation of the hemosome content, monitored at 220 nm.
Arrow, a peak with a retention time similar to a haem standard; inset, the
light absorption spectrum of the same region. (CF) Positive-ion mode
electrospray-ionisation mass spectrometry (ESI-MS) profile of the intact haem
fraction (C) and tandem ESI-MS (ESI-MS/MS) spectra of its daughter ions
(DF). (GI) ESI-MS/MS spectra of standard haem. (D,G) Daughter
ions of m/z 616.4. (E,H) ESI-MS/MS spectra of the daughter ion
m/z 557.4. (F,I) Tandem ESI-MS spectra of the daughter ion
m/z 498.5. (J) Structure of the iron-protoporphyrin IX and the
proposed assignment for its observed daughter ions.