Unnatural porphyrin

The unnatural porphyrin family still fascinates the imagination. This year, to give a flavor for the diversity, there has appeared hybrid calixphyrins <00OL3103>, doubly A-confused porphyrins , unsymmetrical porphyrins attached to a modified 5,10,15,20-tetra (4-(2-trimethylsilylethynyl)phenyl]-21-23-dithiaporphyrin <00TL3709>,... 

Uroporphyrinogen I (16c), a constitutional isomer of uroporphyrinogen III, also plays no direct role in porphyrin and corrin biosynthesis, but this unnatural substrate is methylated to give 17c10c f in the presence of SAM by the methyl transferase of some bacteria. A constitutional type I dihydroisobacteriochlorin can be obtained by methylation of uroporphyrinogen I with methylase Ml. Methyltransferase M1 is able to methylate the unnatural precorrin once more to give the trimethylpyrrocorphin type I.IOc 1... 

Cytochrome c peroxidase has been reversibly resolved into protoheme and apoenzyme moieties (26) by a modification of Teale s acid butanone technique (47). The apoenzyme may be combined with porphyrins and metalloporphyrins to form synthetic holoenzymes containing unnatural prosthetic groups 27-33, 38-40). The apoenzyme (26) and some of the synthetic holoenzymes have been crystallized. 

The plant chlorophylls have a rra s-configuration in the D ring but it has recently been shown that phaeophobides with the unnatural cij-configuration may be prepared by photochemical reduction of zinc porphyrins. ... 

Although uroporphyrinogen I (20), a constitutional isomer of uroporphyrinogen III (14), plays no direct role in porphyrin biosynthesis, this unnatural substrate is methylated in the presence of SAM by the methyl transferases of some bacteria. 

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