Erythrocyte porphobilinogen synthase (delta-aminolaevulinate dehydratase) activity: a reliable and quantitative indicator of lead exposure in humans.
Open Access
- 1 January 1977
- journal article
- research article
- Published by Oxford University Press (OUP) in Clinical Chemistry
- Vol. 23 (1) , 105-111
- https://doi.org/10.1093/clinchem/23.1.105
Abstract
We assessed optimal conditions for assay of porphobillinogen synthase (EC 4.2.1.24) activity in human blood containing abnormally high concentrations of lead. Zn2+and -SH, both required for complete activation of the enzyme, had additive effects. Using a modified method based on these studies, we found blood lead concentration to be strictly proportional to ln(activated/nonactivated) enzyme activity. One brand of commercially available "lead-free" tubes contained a substance that interfered with this relationship. In vitro studies, with the modified assay, showed ALAD to be activated by low concentrations but inactivated by high concentrations of Hg2+, Cd2+, and ethylenediaminetetraacetate. We fouund no genetically influenced differences among unexposed individuals when in(activated/nonactivated) enzyme activities were compared. The technique is suitable for use in screening for lead poisoning in humans.Keywords
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