Abstract
A method to measure the δ-aminolevulinic acid (ALA) synthetase activity in human bonemarrow erythroid cells by incubating the bone-marrow cell homogenate with 14Ca-ketoglutarate has been presented. Studies representing an attempt to obtain the optimal conditions for the enzyme assay and to confirm the reliability of the results of the assay were performed. ALA-synthetase activity in erythroblasts was found decreased in all 4 cases of iron deficiency anemia. In the cases of sideroblastic anemia, the enzyme activity was markedly decreased to less than one-tenth of normal in one case, moderately decreased in 2 cases, and normal in 2 cases. In a case with β-thalassemia, a marked decrease in ALA-synthetase activity was in evidence. In these cases of the sideroblastic anemia or thalassemia with markedly decreased ALA-synthetase activity, a substantial diminution of 14C-glycine incorporation into heme in erythroblasts was also evident. Erythroblasts cf these cases, however, showed only a slight decrease in the heme-synthetase activity. In erythroblasts of patients with erythropoietic protoporphyria, ALA-synthetase activity was found to be within normal limits in 2 cases, and apparently increased in one case.
