title: Enzyme abnormalities in the porphyrias.
abstract: Evidence is presented that each of the porphyrias represents a different inborn error of metabolism in haem biosynthesis. Control of the pathway takes place by feedback repression and inhibition by haem of delta-aminolaevulinic-acid synthase. It is suggested that insituations where the activity of this enzyme is derepressed, prophobilinogen deaminase represents a secondary control step.
mesh_terms: D000624:5-Aminolevulinate Synthetase / Q000172:deficiency* / Q000378:metabolism; D000208:Acute Disease; D000642:Ammonia-Lyases / Q000378:metabolism*; D002908:Chronic Disease; D004796:Clinical Enzyme Tests; D003304:Coproporphyrinogen Oxidase / Q000378:metabolism; D005294:Ferrochelatase / Q000378:metabolism; D006418:Heme / Q000096:biosynthesis; D006801:Humans; D011163:Hydroxymethylbilane Synthase / Q000378:metabolism*; D007962:Leukocytes / Q000201:enzymology; D008954:Models, Biological; D000623:Porphobilinogen Synthase / Q000378:metabolism; D011164:Porphyrias / Q000145:classification / Q000201:enzymology / Q000209:etiology*; D011166:Porphyrins / Q000378:metabolism; D014575:Uroporphyrinogen Decarboxylase / Q000378:metabolism
chemical_list: D011166:Porphyrins; D006418:Heme; D003304:Coproporphyrinogen Oxidase; D000624:5-Aminolevulinate Synthetase; D011163:Hydroxymethylbilane Synthase; D014575:Uroporphyrinogen Decarboxylase; D000623:Porphobilinogen Synthase; D000642:Ammonia-Lyases; D005294:Ferrochelatase