Catabolism of porphobilinogen by etiolated barley leaves

When 2,4-¹⁴C]porphobilinogen (PBG) or 2 (aminomethyl),5-¹⁴C]PBG is administered to etiolated barley (Hordeum vulgare L. var. Larker) leaves in darkness, label becomes incorporated into CO₂, organic and amino acids, sugars, lipids, and proteins during a 4-hour incubation. Less than 1% of the label, however, is incorporated into porphyrins. The rate of ¹⁴CO₂ evolution from leaves fed 2,4-¹⁴C]PBG is strongly inhibited by anaerobiosis but is unaffected by aminooxyacetic acid, while the rate of ¹⁴CO₂ evolution from 2(aminomethyl),5-¹⁴C]PBG is strongly inhibited by aminooxyacetic acid but is not affected by anaerobiosis.