The biogenesis of porphyrins. The distribution of 15N in the ring system

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Abstract
Methylethylmaleic acid imide and hematinic acid imide, 2 oxidation products of mesoporphyrin, were synthesized and the physical constants determined. The oxidation of mesoporphyrin by chromic anhydride was investigated, and conditions were established which permit the isolation of methylethylmaleic acid imide and hematinic acid imide on a micro-scale. This method was applied to the degradation of mesoporphyrin obtained from rabbits fed glycine containing an excess of Nl5. The results show that the acidic and non-acidic pyrrole nuclei in hemin have the same or closely similar isotope ratios. Ethanolamine containing an excess of N15 was fed to rats. The hemin obtained had a much lower Nl5 content than that of control animals which had received a slightly smaller amt. of labelled glycine. It is concluded that the N of ethanolamine is not used to any marked extent in the synthesis of protoporphyrin.