Porphyrin Metabolism

Porphyrins are tetrapyrrole, macrocyclic organic compounds that are essential for life on the Earth. Metallated porphyrins participate in a variety of reactions including oxidation/reduction reactions, sulfur and nitrogen reduction, methane production, methyl group transfer, gas sensing, and light-harvesting reactions. All porphyrins are derived from a common precursor,δ-aminolevulinic acid, and their synthesis proceeds along a common pathway for several steps before diverging to form various metallated tetrapyrrole compounds which include heme, chlorophyll and bacteriochlorophyll, siroheme, heme d₁, and factor F₄₃₀. In addition, coenzyme B₁₂, which is a corrin rather than a porphyrin, is also a product of the branched pathway. Regulation of the synthesis of porphyrins is complex and not completely understood in most cases, although it is clear that the regulation of the synthesis of the common precursor serves a primary role. Deficiencies in porphyrin metabolism have serious consequences on organismal growth and development and are of biomedical and agricultural interest. The catabolism of metalloporphyrins is essential for the removal of potentially toxic compounds, but can also provide benefits to the host organism.