title: Delta-aminolaevulinic acid metabolism in normal and lead-exposed humans.
abstract: The activity of the haem biosynthetic enzymes delta-aminolaevulinic acid synthetase (ALA.S) and delta-aminolaevulinic acid dehydratase (ALA.D) were measured in the peripheral blood of a group of lead workers and control subjects. The haem precursor delta-aminolaevulinic acid (ALA) was measured in blood and urine, whilst lead levels were measured in whole blood. The inter-relationships between all these parameters were examined and quantified. The results demonstrate that above a blood lead concentration of 2 mumole/l and below an erythrocyte ALA.D activity of 18 nmole ALA utlized/min/ml red blood cells (R.B.C.), Haem synthesis is depressed to such an extent that the activity of leucocyte ALA.S, the rate-limiting enzyme of haem biosynthesis, is increased by negative feedback.
mesh_terms: D000624:5-Aminolevulinate Synthetase / Q000097:blood; D000293:Adolescent; D000328:Adult; D000622:Aminolevulinic Acid / Q000097:blood / Q000378:metabolism* / Q000652:urine; D004912:Erythrocytes / Q000201:enzymology; D005260:Female; D006801:Humans; D007855:Lead Poisoning / Q000378:metabolism*; D007962:Leukocytes / Q000201:enzymology / Q000648:ultrastructure; D007982:Levulinic Acids / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D008928:Mitochondria / Q000201:enzymology; D000623:Porphobilinogen Synthase / Q000097:blood
chemical_list: D007982:Levulinic Acids; D000622:Aminolevulinic Acid; D000624:5-Aminolevulinate Synthetase; D000623:Porphobilinogen Synthase