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Porphobilinogen (PBG) is an organic compound that occurs in living organisms as an intermediate in the biosynthesis of porphyrins, which include critical substances like hemoglobin and chlorophyll. [ 1 ]
It catalyzes the following reaction, the second step of the biosynthesis of porphyrin: 2 5-Aminolevulinic acid porphobilinogen + 2 H 2 O. It therefore catalyzes the condensation of 2 molecules of 5-aminolevulinate to form porphobilinogen (a precursor of heme, cytochromes and other hemoproteins). This reaction is the first common step in the ...
The most well-known health issue involving porphobilinogen deaminase is acute intermittent porphyria, an autosomal dominant genetic disorder where insufficient hydroxymethylbilane is produced, leading to a build-up of porphobilinogen in the cytoplasm. This is caused by a gene mutation that, in 90% of cases, causes decreased amounts of enzyme.
In non-photosynthetic eukaryotes such as animals, insects, fungi, and protozoa, as well as the α-proteobacteria group of bacteria, the committed step for porphyrin biosynthesis is the formation of δ-aminolevulinic acid (δ-ALA, 5-ALA or dALA) by the reaction of the amino acid glycine with succinyl-CoA from the citric acid cycle.
Heme is produced in all cells, but 80% of all heme is produced in erythropoietic cells in bone marrow and 15% in parenchymal cells in the liver, where turnover of hemoproteins is high. In AIP, over 100 mutations have been identified on the long arm of chromosome 11 at the HMBS gene, which codes for the cytoplasmic enzyme porphobilinogen ...
δ-Aminolevulinic acid (also dALA, δ-ALA, 5ALA or 5-aminolevulinic acid), an endogenous non-proteinogenic amino acid, is the first compound in the porphyrin synthesis pathway, the pathway that leads to heme [3] in mammals, as well as chlorophyll [4] in plants.
HMB is generated from four molecules of porphobilinogen by the enzyme porphobilinogen deaminase: [2] The enzyme uroporphyrinogen III synthase closes the chain to form uroporphyrinogen III : [ 2 ] Uroporphyrinogen III is a porphyrinogen , which is a class of compounds with the hexahydroporphine macrocycle .
In the biosynthesis of porphyrins, the parent porphyrinogen is dehydrogenated by protoporphyrinogen oxidase. Because of their limited delocalization, porphyrinogens are colorless. Loss of all four central hydrogen atoms in the core yields a tetravalent anion that can act as a ligand to metal cations, creating a coordination compound . [ 3 ]