Modification of Naturally Occurring Porphyrins

For monomeric host porphyrin framework, we may start from natural porphyrins such as protoporphyrin IX and its derivatives. In earlier times, the 3- and 8-vinyl and 13- and 17-propionates of protoporphyrin IX were subjected to simple chemical mc ifications like reduction, addition and condensation. The first chemical modification for synthesis of heme protein models reported by Lautch et al. is condensation of an oligopeptide with the two propionates. In order to mimic the proximity of the heme, terminal His or Cys of oligopeptide linked to the 13- and 17-propionates of heme can coordinate to the heme iron as axial ligands. 

Reconstitution of apoproteins or apoenzymes with various synthetic hemes has been widely investigated in order to elucidate the effect of structural factors of the heme on the protein functions. If protoheme chemically modified at the 13- and 17-propionates forms a stable reconstituted 

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