Hematoporphyrin IX, a probable precursor of protoporphyrin in the biosynthetic chain of heme and chlorophyll.

In the preceding paper (1) the isolation and culture of Chlorella WEB-17 was described. Evidence was presented that this mutant produced three dicarboxylic porphyrins in relatively large amounts. In this paper we report the isolation from the porphyrin mixture of one of these dicarboxylic porphyrins and its characterization as hematoporphyrin isomer IX (Fig. 1). Hematoporphyrin has not previously been reported as a naturally occurring porphyrin. Although traces of porphyrins of low HCl number arise when tissues rich in hemin have been incubated under sterile or non-sterile conditions for prolonged periods of time (2, 3), no evidence supports the statements that hematoporphyrin is one of these pigments. Fe hematoporphyrin or hematoporphyrin has been shown to arise when the prosthetic group of cytochrome c is split off the protein by certain treatments, the thio ether linkages of porphyrin c side chains being replaced by OH groups (4-6).