Studies on ferrochelatase. 2. An in vestigation of the role offerrochelatase in the biosynthesis of various haem prosthetic groups

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Abstract
Emasol 4130, which increases the solubility of porphyrins in aqueous media at pH 7.8, was used to facilitate a study of enzymic heme formation. Some reduced pyridine hemochromogens were prepared and details of the difference spectra of their reduced and oxidized forms were recorded. Fresh pig-liver extract with Fe2+ ions converted deutero-, meso- (IX) meso- (I), hemato-, monoformyldeutero-, monohydroxymethyldeut-ero, mono-[beta]-hydroxyethylmonovinyldeutero-, proto- and chlorocruoro-porphyrin into the corresponding haems. Of the other dicarboxylic compounds tested, porphyrin a and diformyl-deuteroporphyrin were not used. Both the tetracarboxylic compounds, coproporphyrin and porphyrin c, and the monocarboxylic pyrroporphyrin were likewise inactive. The dimethyl esters of mesoporphyrin DC and deuteroporphyrin were not substrates. Heme formation by aged pig-liver extracts differed from that in fresh extracts. Ferrochelatase activity has been found in extracts of several micro-organisms and its significance in the biosynthesis of haem prosthetic groups has been discussed. Evidence has been obtained for the existence of several forms of ferrochelatase in different organisms; pig -liver extract itself may contain more than one form of the enzyme.