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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.
R A Mitchell, and
J E Drake, and
L A Wittlin, and
T A Rejent
April 1985,
Clinical chemistry,
R A Mitchell, and
J E Drake, and
L A Wittlin, and
T A Rejent
May 1975,
The Journal of laboratory and clinical medicine,
R A Mitchell, and
J E Drake, and
L A Wittlin, and
T A Rejent
May 1982,
Revista medica de Chile,
R A Mitchell, and
J E Drake, and
L A Wittlin, and
T A Rejent
November 1975,
Clinical chemistry,
R A Mitchell, and
J E Drake, and
L A Wittlin, and
T A Rejent
September 1999,
British journal of haematology,
R A Mitchell, and
J E Drake, and
L A Wittlin, and
T A Rejent
October 1988,
Biological chemistry Hoppe-Seyler,
R A Mitchell, and
J E Drake, and
L A Wittlin, and
T A Rejent
August 1972,
Archives of environmental health,
R A Mitchell, and
J E Drake, and
L A Wittlin, and
T A Rejent
January 1978,
Biochemical Society transactions,
R A Mitchell, and
J E Drake, and
L A Wittlin, and
T A Rejent
September 1972,
The Biochemical journal,
R A Mitchell, and
J E Drake, and
L A Wittlin, and
T A Rejent
April 1975,
Nihon eiseigaku zasshi. Japanese journal of hygiene,
