title: Highlights in haem biosynthesis.
abstract: The haem biosynthesis pathway continues to provide surprises, from the first enzyme, 5-aminolaevulinic acid synthase, the mRNA of which contains an iron-responsive element, to the last, ferrochelatase, that contains an iron sulphur cluster. 5-Aminolaevulinate dehydratase from animals are zinc-dependent enzymes while those from plants require magnesium. The first X-ray structure of a haem synthesis enzyme, porphobilinogen deaminase, has not only yielded clues about the mechanism of tetrapyrrole assembly but has also provided insight into the molecular basis of the human disease acute intermittent porphyria. Evidence is growing to suggest that a previously unsuspected alternative haem pathway may exist.
authors.forename: P M
authors.initials: PM
authors.lastname: Jordan
mesh_terms: D000624:5-Aminolevulinate Synthetase / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003304:Coproporphyrinogen Oxidase / Q000378:metabolism; D006418:Heme / Q000096:biosynthesis*; D006801:Humans; D011163:Hydroxymethylbilane Synthase / Q000378:metabolism; D019751:Intramolecular Transferases; D007535:Isomerases / Q000378:metabolism; D008956:Models, Chemical; D008969:Molecular Sequence Data; D000623:Porphobilinogen Synthase / Q000378:metabolism
chemical_list: D006418:Heme; D003304:Coproporphyrinogen Oxidase; D000624:5-Aminolevulinate Synthetase; D011163:Hydroxymethylbilane Synthase; D000623:Porphobilinogen Synthase; D007535:Isomerases; D019751:Intramolecular Transferases; C061049:glutamate-1-semialdehyde 2,1-aminomutase