Activity of erythrocyte delta-aminolevulinic acid dehydratase in the female cynomolgus monkey (Macaca fascicularis): kinetic analysis in control and lead-exposed animals.
Kinetic analysis of erythrocyte delta-aminolevulinic acid dehydrase (delta-ALAD) from female cynomolgus monkeys revealed differences in pH optimum and Michaelis constants according to their exposure to lead. In vitro incubation of delta-ALAD with 5 mM dithiothreitol (DTT) or 100-200 microM zinc resulted in an enhanced enzyme activity being expressed. These effects were additive. Activation with DTT or zinc resulted in the abolition of pH differences between control and exposed animals and revealed an increased quantity of enzyme in exposed animals. delta-ALAD in control monkeys was observed to be very sensitive to inhibition by lead in vitro with an apparent inhibition constant (Ki) of 0.12 microM. The effect of lead on monkey delta-ALAD enzyme kinetics is similar to that seen with human samples and thus is a useful model for measuring biological response to lead exposure.
Dorward
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A
Department of Biology, McMaster University, Hamilton, Ontario, Canada.
Yagminas
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AP
D000818:Animals; D004229:Dithiothreitol / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004912:Erythrocytes / Q000187:drug effects / Q000201:enzymology*; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007854:Lead / Q000097:blood / Q000633:toxicity*; D008252:Macaca fascicularis; D000623:Porphobilinogen Synthase / Q000037:antagonists & inhibitors / Q000097:blood*; D015032:Zinc / Q000494:pharmacology
D007854:Lead; D000623:Porphobilinogen Synthase; D015032:Zinc; D004229:Dithiothreitol