Inhibition of Porphobilinogen Synthase Activity by 4,5-Dioxovalerate

摘要

The effect of 4,5-dioxovaleric acid on the activity of porphobilinogen (PBG) synthase (formerly 5-aminolevulinic acid dehydratase, EC 4.2.1.24) of the porphyrin synthetic pathway was studied with the enzyme purified fromChlorella regularis. 4,5-Dioxovaleric acid, a metabolite of 5-aminolevulinic acid, competitively inhibited PBG synthase with aKivalue of 1.4 mm. The concentration for the half inhibition of 4,5-dioxovaleric acid (7 mm) was slightly lower than that for the known competitive inhibitor, levulinic acid (12 mm).