[Delta-aminolevulinic acid dehydratase (ALAD) activity in red blood cells in different ages (2nd report). An elucidation of the factors decreasing ALAD activity by aging of rabbit's red blood cells].
ALAD activity is decreased by lead as well as by the aging of red cells. Experiments were performed to clarify the factors decreasing ALAD activity by the aging of red blood cells in rabbits. Measurements were conducted on ALAD activity and lead contents in young and old cells. Lead content in both young and old RBC groups ranged from 32 to 68 and 61 to 115 ng/10(10) RBC respectively. The old cells had a higher range of lead (21 to 50 ng) than the young cells. The result revealed that the increased lead content was not the main cause of decreased ALAD activity. Fully activated ALAD activity in both groups was measured by adding zinc ion (0.25 mM) and dithiothreitol (10 mM). The activity ratio of young to old cells was 1 to 0.6, suggesting that the decrease in enzyme depended on aging. The fully activated ALAD activity and oxidation of this enzyme were compared among erythroblasts, young and old cells. The ALAD activity decreased by 5-19.6% in young red cells and by 37-67% in old ones against that of erythroblasts. Treatment of the enzyme with dithiothreitol increased the activity by 12.6-19.4% in young red cells and by 24.2-27.3% in old ones. No increase in the enzyme activity in erythroblasts with dithiothreitol treatment was observed. These results suggest that the decreased activity of ALAD by aging is due mainly to the decrease of enzyme amount, partly to the oxidation of sulfhydryl groups of this enzyme, and only slightly to the increase in the blood lead.
D000818:Animals; D004229:Dithiothreitol / Q000494:pharmacology; D004900:Erythroblasts / Q000201:enzymology; D004905:Erythrocyte Aging; D004912:Erythrocytes / Q000201:enzymology*; D007854:Lead / Q000097:blood; D000623:Porphobilinogen Synthase / Q000097:blood*; D011817:Rabbits; D012156:Reticulocytes / Q000201:enzymology; D015032:Zinc / Q000494:pharmacology
D007854:Lead; D000623:Porphobilinogen Synthase; D015032:Zinc; D004229:Dithiothreitol