Abstract
The effects of O2 concentration on porphyrin biosynthesis from -aminolevulinic acid and porphobilinogen were studied in whole hemolysates of chicken erythrocytes and in supernatants from these preparations. These studies show that concentrations of O2 higher than 5-7% (v/v) inhibit the conversion of porphobilinogen into uroporphyrinogen. This inhibition can be reversed by lowering the concentration of O2. The stability of uro-, copro- and protoporphy-rins to high concentrations of O2 was demonstrated.