Biosynthesis of the natural (type-III) porphyrins: proof that rearrangement occurs after head-to-tail bilane formation
Abstract
The aminomethylbilane corresponding to head-to-tail combination of four porphobilinogen units is unambiguously synthesised and it is converted (rearranged) by the deaminase–cosynthetase enzyme system into uro'gen-III, the precursor of the natural porphyrins, chlorins, and corrins; 13C-labelling establishes the specificity of the conversion.