Alterations in the Activity of Enzymes of Haem Biosynthesis in Lead Poisoning and Acute Hepatic Porphyria

Abstract

The activities of 6 of the enzymes of heme biosynthesis were assayed in peripheral blood from patients with Pb poisoning, acute intermittent porphyria or hereditary coproporphyria. Compared with normal subjects the lead-poisoned subjects had highly significant depression of .delta.-aminolevulinate dehydratase, coproporphyrinogen oxidase and ferrochelatase. Pb-poisoned subjects had highly significant elevation of .delta.-aminolevulinate synthase activity. .delta.-Aminolevulinate synthase activity was inversely related to the hemoglobin concentration. Increased .delta.-aminolevulinate synthase and decreased .delta.-aminolevulinate dehydratase activity was found in acute intermittent porphyria. Increased .delta.-aminolevulinate synthase, normal porphobilinogen deaminase and uroporphyrinogen decarboxylase and decreased coproporphyrinogen oxidase was found in both lead poisoning and hereditary coproporphyria. These enzyme changes explained the recognized patterns of porphyrins and porphyrin precursors in blood and urine in these conditions.