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Delta-Aminolevulinic Acid Dehydratase Assay
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1982
Year
δ‑Aminolevulinic acid (ALA) dehydratase catalyzes the synthesis of porphobilinogen (PBG) from two molecules of ALA. The study presents a semimicro colorimetric method for determining ALA dehydratase activity in various tissues and discusses the effects of activators and inhibitors. The assay employs a semimicro colorimetric approach to quantify ALA dehydratase activity in tissue homogenates. In adult male rat liver, enzyme activity was 2.22 and 1.94 μmol PBG g⁻¹ h⁻¹ with or without dithiothreitol, the assay remained linear for at least 2.5 h and up to 2.5 mg tissue, and the Kₘ for ALA was 4.0 × 10⁻⁴ M with a pH optimum of 6.2–6.4.
δ-Aminolevulinic acid (ALA) dehydratase catalyzes the synthesis of porphobilinogen (PBG) from two molecules of ALA. A semimicro method for the colorimetric determination of ALA dehydratase is presented and applied to various tissues. The enzyme activity in adult male rat liver was 2.22 and 1.94 μmol PBG formed/g liver/h for homogenates assayed with or without dithiothreitol, respectively. The assay was linear for at least 2.5 h and for up to 2.5 mg tissue per assay. The K(m) for ALA was 4.0 X 10^-4 M and the pH optimum was 6.2-6.4. The effects of activators and inhibitors on enzyme activity are discussed.